World on track for 2015 to 2019 to be 5 hottest years on record
by World Meteorological Organization, agencies
12:58pm 5th Aug, 2019
23 Sep. 2019
Global Climate in 2015-2019: Climate change accelerates. (WMO)
The tell-tale signs and impacts of climate change – such as sea level rise, ice loss and extreme weather – increased during 2015-2019, which is set to be the warmest five-year period on record, according to the World Meteorological Organization (WMO). Greenhouse gas concentrations in the atmosphere have also increased to record levels, locking in the warming trend for generations to come.
The WMO report on The Global Climate in 2015-2019, released to inform the United Nations Secretary-General’s Climate Action Summit, says that the global average temperature has increased by 1.1°C since the pre-industrial period, and by 0.2°C compared to 2011-2015.
The climate statement – which covers until July 2019 - was released as part of a high-level synthesis report from leading scientific institutions United in Science under the umbrella of the Science Advisory Group of the UN Climate Summit 2019. The report provides a unified assessment of the state of Earth system under the increasing influence of climate change, the response of humanity this far and projected changes of global climate in the future. It highlights the urgency and the potential of ambitious climate action in order to limit potentially irreversible impacts.
An accompanying WMO report on greenhouse gas concentrations shows that 2015-2019 has seen a continued increase in carbon dioxide (CO2) levels and other key greenhouse gases in the atmosphere to new records, with CO2 growth rates nearly 20% higher than the previous five years. CO2 remains in the atmosphere for centuries and in the ocean for even longer.
Preliminary data from a subset of greenhouse gas observational sites for 2019 indicate that CO2 global concentrations are on track to reach or even exceed 410 ppm by the end of 2019.
“Climate change causes and impacts are increasing rather than slowing down,” said WMO Secretary-General Petteri Taalas, who is co-chair of the Science Advisory Group of the UN Climate Summit.
“Sea level rise has accelerated and we are concerned that an abrupt decline in the Antarctic and Greenland ice sheets, which will exacerbate future rise. As we have seen this year with tragic effect in the Bahamas and Mozambique, sea level rise and intense tropical storms led to humanitarian and economic catastrophes,” he said.
“The challenges are immense. Besides mitigation of climate change, there is a growing need to adapt. According to the recent Global Adaptation Commission report the most powerful way to adapt is to invest in early warning services, and pay special attention to impact-based forecasts,” he said.
“It is highly important that we reduce greenhouse gas emissions, notably from energy production, industry and transport. This is critical if we are to mitigate climate change and meet the targets set out in the Paris Agreement,” he said.
“To stop a global temperature increase of more than 2 degrees Celsius above pre-industrial levels, the level of ambition needs to be tripled. And to limit the increase to 1.5 degrees, it needs to be multiplied by five,” he said.
Sea level rise:
Over the five-year period May 2014 -2019, the rate of global mean sea-level rise has amounted to 5 mm per year, compared with 4 mm per year in the 2007-2016 ten-year period.
This is substantially faster than the average rate since 1993 of 3.2 mm/year. The contribution of land ice melt from the world glaciers and the ice sheets has increased over time and now dominate the sea level budget, rather than thermal expansion.
Throughout 2015-2018, the Arctic’s average September minimum (summer) sea-ice extent was well below the 1981-2010 average, as was the average winter sea-ice extent. The four lowest records for winter occurred during this period. Multi-year ice has almost disappeared.
Antarctic February minimum (summer) and September maximum (winter) sea-ice extent values have become well below the 1981-2010 average since 2016. This is in contrast to the previous 2011-2015 period and the long term 1979-2018 period. Antarctic summer sea ice reached its lowest and second lowest extent on record in 2017 and 2018, respectively, with 2017 also being the second lowest winter extent.
The amount of ice lost annually from the Antarctic ice sheet increased at least six-fold, from 40 Gt per year in 1979-1990 to 252 Gt per year in 2009-2017.
The Greenland ice sheet has witnessed a considerable acceleration in ice loss since the turn of the millennium.
For 2015-2018, the World Glacier Monitoring Service (WGMS) reference glaciers indicates an average specific mass change of −908 mm water equivalent per year, higher than in all other five-year periods since 1950.
Ocean heat and acidity:
More than 90 % of the excess heat caused by climate change is stored in the oceans. 2018 had the largest ocean heat content values on record measured over the upper 700 meters, with 2017 ranking second and 2015 third.
The ocean absorbs around 30% of the annual anthropogenic emissions of CO2, thereby helping to alleviate additional warming. The ecological costs to the ocean, however, are high, as the absorbed CO2 reacts with seawater and changes the acidity of the ocean. There has been an overall increase in acidity of 26% since the beginning of the industrial revolution.
More than 90 % of the natural disasters are related to weather. The dominant disasters are storms and flooding, which have also led to highest economic losses. Heatwaves and drought have led to human losses, intensification of forest fires and loss of harvest.
Heatwaves, which were the deadliest meteorological hazard in the 2015-2019 period, affecting all continents and resulting in numerous new temperature records. Almost every study of a significant heatwave since 2015 has found the hallmark of climate change, according to the report.
The largest economic losses were associated with tropical cyclones. The 2017 Atlantic hurricane season was one of the most devastating on record with more than US$ 125 billion in losses associated with Hurricane Harvey alone. On the Indian Ocean, in March and April 2019, unprecedented and devastating back-to-back tropical cyclones hit Mozambique.
Wildfires are strongly influenced by weather and climate phenomena. Drought substantially increases the risk of wildfire in most forest regions, with a particularly strong influence on long-lived fires. The three largest economic losses on record from wildfires have all occurred in the last four years.
In many cases, fires have led to massive releases of carbon dioxide to the atmosphere. Summer 2019 saw unprecedented wildfires in the Arctic region. In June alone, these fires emitted 50 megatons (Mt) of carbon dioxide into the atmosphere. This is more than was released by Arctic fires in the same month from 2010 to 2018 put together.
There were also massive forest fires in Canada and Sweden in 2018. There were also widespread fires in the non-renewable tropical rain forests in Southern Asia and Amazon, which have had impacts on the global carbon budget.
Climate change and extreme events
According to the Bulletin of the American Meteorological Society, over the period 2015 to 2017, 62 of the 77 events reported show a significant anthropogenic influence on the event’s occurrence, including almost every study of a significant heatwave. An increasing number of studies are also finding a human influence on the risk of extreme rainfall events.
22 Sep. 2019
Landmark United in Science report informs Climate Action Summit
The world’s leading climate science organizations have joined forces to produce a landmark new report for the United Nations Climate Action Summit, underlining the glaring – and growing – gap between agreed targets to tackle global warming and the actual reality.
The report, United in Science, includes details on the state of the climate and presents trends in the emissions and atmospheric concentrations of the main greenhouse gases. It highlights the urgency of fundamental socio-economic transformation in key sectors such as land use and energy in order to avert dangerous global temperature increase with potentially irreversible impacts. It also examines tools to support both mitigation and adaptation.
“The Report provides a unified assessment of the state of our Earth system under the increasing influence of anthropogenic climate change, of humanity’s response thus far and of the far-reaching changes that science projects for our global climate in the future.
The scientific data and findings presented in the report represent the very latest authoritative information on these topics,” said the Science Advisory Group to the UN Secretary-General’s Climate Action Summit.
“It highlights the urgent need for the development of concrete actions that halt the worst effects of climate change.”
The Science Advisory Group comprises highly recognized and respected natural and social scientists, with expertise in different aspects of climate change, including on mitigation and adaptation.
The report, which was coordinated by the World Meteorological Organization, aims to present a “transparent envelope” of authoritative and actionable cutting-edge science.
The synthesis report consists of short summaries from contributing agencies: the World Meteorological Organization (WMO), Global Atmosphere Watch, the United Nations Environment Programme (UNEP), Global Carbon Project, the Intergovernmental Panel on Climate Change (IPCC), Future Earth, Earth League and the Global Framework for Climate Services.
The synthesis is complemented by longer, individual reports, presented as a package to world leaders at the Climate Action Summit on 23 September.
Highlights from the report include:
The Global Climate in 2015-2019 - World Meteorological Organization (WMO)
Warmest five-year period on record
The average global temperature for 2015–2019 is on track to be the warmest of any equivalent period on record. It is currently estimated to be 1.1°Celsius (± 0.1°C) above pre-industrial (1850–1900) times. Widespread and long-lasting heatwaves, record-breaking fires and other devastating events such as tropical cyclones, floods and drought have had major impacts on socio-economic development and the environment.
Continued decrease of sea ice and ice mass
Arctic summer sea-ice extent has declined at a rate of approximately 12% per decade during 1979-2018. The four lowest values for winter sea-ice extent occurred between 2015 and 2019.
Overall, the amount of ice lost annually from the Antarctic ice sheet increased at least six-fold between 1979 and 2017. Glacier mass loss for 2015-2019 is the highest for any five-year period on record.
Sea-level rise is accelerating, sea water is becoming more acidic
The observed rate of global mean sea-level rise accelerated from 3.04 millimeters per year (mm/yr) during the period 1997–2006 to approximately 4mm/yr during the period 2007–2016. This is due to the increased rate of ocean warming and melting of the Greenland and West Antarctica ice sheets. There has been an overall increase of 26% in ocean acidity since the beginning of the industrial era.
Record Greenhouse Gas Concentrations in the Atmosphere - WMO Global Atmosphere Watch
Levels of the main long-lived greenhouse gases, carbon dioxide (CO2), methane (CH4)) and nitrous oxide (N2O) have reached new highs.
The last time Earth’s atmosphere contained 400 parts per million CO2 was about 3-5 million years ago, when global mean surface temperatures were 2-3°C warmer than today, ice sheets in Greenland and West Antarctica melted, parts of East Antarctica ice had retreated, all causing global see level rise of 10-20m compared with today.
In 2018, global CO2 concentration was 407.8 parts per million (ppm), 2.2 ppm higher than 2017. Preliminary data from a subset of greenhouse gas monitoring sites for 2019 indicate that CO2 concentrations are on track to reach or even exceed 410 parts per million (ppm) by the end of 2019.
Global Carbon Budget - Global Carbon Project
Carbon dioxide emissions grew 2% and reached a record high of 37 billion tonnes of CO2 in 2018. There is still no sign of a peak in global emissions, even though they are growing slower than the global economy.
Current economic and energy trends suggest that emissions will be at least as high in 2019 as in 2018. Global GDP is expected to grow at 3.2% in 2019, and if the global economy decarbonized at the same rate as in the last 10 years, that would still lead to an increase in global emissions.
Despite extraordinary growth in renewable fuels over the past decade, the global energy system is still dominated by fossil fuel sources. The annual increase in global energy use is greater than the increase in renewable energy, meaning the fossil fuel use continues to grow. This growth needs to halt immediately.
The net-zero emissions needed to stabilize the climate requires both an acceleration in use of non-carbon energy sources and a rapid decline in the global share of fossil fuels in the energy mix. This dual requirement illustrates the scale of the challenge.
Natural CO2 sinks, such as vegetation and oceans, which remove about half of all emissions from human activities, will become less efficient at doing so. This underscores the need to reduce deforestation and expand natural CO2 sinks, particularly those in forests and soils that can be improved by better management and habitat restoration.
The emissions gap – where we are and where we need to be, report from United Nations Environment Programme (UNEP)
The UNEP Emissions Gap Reports, with the tenth edition being published this November, assess the latest scientific studies on current and estimated future greenhouse gas emissions; they compare these with the emission levels permissible for the world to progress on a least-cost pathway to achieve the goals of the Paris Agreement. This difference between “where we are likely to be and where we need to be” is known as the emissions gap.
Global emissions are not estimated to peak by 2030, let alone by 2020, if current climate policies and ambition levels of the Nationally Determined Contributions (NDCs) are maintained. Preliminary findings from the Emissions Gap Report 2019 indicate that greenhouse gas emissions continued to rise in 2018.
The emissions gap in 2030 between emission levels under full implementation of conditional Nationally Determined Contributions (NDCs) and levels consistent with least-cost pathways to the 2°C target is 13 GtCO2e.
If just the unconditional NDCs are implemented, the gap increases to 15 GtCO2e. The gap in the case of the 1.5°C target and 2°C target is 29 GtCO2e and 32 GtCO2e respectively.
Current NDCs are estimated to lower global emissions in 2030 by up to 6 GtCO2e compared to a continuation of current policies. This level of ambition needs to be roughly tripled to align with the 2°C limit and must be increased around fivefold to align with the 1.5°C limit.
Implementing unconditional NDCs, and assuming that climate action continues consistently throughout the twenty-first century, would lead to a global mean temperature rise between 2.9°C and 3.4°C by 2100 relative to pre-industrial levels.
If NDC ambitions are not increased immediately and backed up by action, exceeding the 1.5°C goal can no longer be avoided. If the emissions gap is not closed by 2030, it is very plausible that the goal of a well-below 2°C temperature increase is also out of reach.
A substantial part of the technical potential can be realized through scaling up and replicating existing, well-proven policies – such as switching to renewable energy and reforestation - that simultaneously contribute to key sustainable development goals.
Intergovernmental Panel on Climate Change (IPCC)
Three IPCC Special Reports released in 2018 and 2019 assess complementary and specific aspects of climate change, ahead of the Sixth Assessment Report.
The Special Report on Global Warming of 1.5°C states that limiting warming to 1.5ºC is not physically impossible but would require unprecedented transitions in all aspects of society. There are clear benefits to keeping warming to 1.5 ºC compared to 2 ºC or higher. Every bit of warming matters.
Limiting warming to 1.5ºC can go hand in hand with reaching other world goals such as achieving sustainable development and eradicating poverty.
The Special Report on Climate Change and Land stressed that land is already under growing human pressure and climate change is adding to these pressures. At the same time, keeping global warming to well below 2ºC can be achieved only by reducing greenhouse gas emissions from all sectors including land and food.
"The report shows that better land management can contribute to tackling climate change, but land is not the only solution. Reducing greenhouse gas emissions from all sectors including energy is essential if global warming is to be kept as close as possible to 1.5ºC above pre-industrial levels."
On 25 September 2019, the IPCC is due to release the Special Report on the Ocean and Cryosphere in a Changing Climate.
Climate Insights - Future Earth and Earth League
Consolidated evidence reinforces human influence as the dominant cause of changes to the Earth system, in a new geological epoch, the Anthropocene.
Growing climate impacts increase the risks of crossing critical tipping points. These refer to thresholds that, if crossed, lead to far-reaching, in some cases abrupt and/or irreversible changes.
There is a growing recognition that climate impacts are hitting harder and sooner than climate assessments indicated even a decade ago.
As climate change intensifies, cities are particularly vulnerable to impacts such as heat stress and can play a key role in reducing emissions locally and globally.
Strategies for mitigation and for upscaling adaptive risk management are necessary going forward. Neither is adequate in isolation given the pace of climate change and magnitude of its impacts.
Only immediate and all-inclusive action encompassing: deep de-carbonization complemented by ambitious policy measures, protection and enhancement of carbon sinks and biodiversity, and efforts to remove CO2 from the atmosphere, will enable us to meet the Paris Agreement.
Global Framework for Climate Services
Climate and early warning information services should underpin decision-making on climate action for adaptation.
According to new data from the World Meteorological Organization and Copernicus Climate Change Programme, July at least equalled, if not surpassed, the hottest month in recorded history. This follows the warmest ever June on record.
The data from the Copernicus Climate Change Programme, run by the European Centre for Medium-Range Weather Forecasts, is fed into the UN system by WMO. The figures show that, based on the first 29 days of the month, July 2019 will be on par with, and possibly marginally warmer than the previous warmest July, in 2016, which was also the warmest month ever.
The latest figures are particularly significant because July 2016 was during one of the strongest occurrence of the El Niño phenomenon, which contributes to heightened global temperatures. Unlike 2016, 2019 has not been marked by a strong El Niño.
“We have always lived through hot summers. But this is not the summer of our youth. This is not your grandfather’s summer,” said UN Secretary-General António Guterres, announcing the data in New York.
July 2019 will be around 1.2°C warmer than the pre-industrial era, according to the data.
“All of this means that we are on track for the period from 2015 to 2019 to be the five hottest years on record. This year alone, we have seen temperature records shattered from New Delhi to Anchorage, from Paris to Santiago, from Adelaide and to the Arctic Circle. If we do not take action on climate change now, these extreme weather events are just the tip of the iceberg. And, indeed, the iceberg is also rapidly melting,” Mr Guterres said.
“Preventing irreversible climate disruption is the race of our lives, and for our lives. It is a race that we can and must win,” he underlined.
Exceptional heat has been observed across the globe in recent week, with a string of European countries logging record highs temperatures that have caused disruption to transport and infrastructure and stress on people''s health and the environment. As the heat dome spread northwards through Scandinavia and towards Greenland, it accelerated the already above average rate of ice melt.
“July has re-written climate history, with dozens of new temperature records at local, national and global level,” said WMO Secretary-General Petteri Taalas.
“The extraordinary heat was accompanied by dramatic ice melt in Greenland, in the Arctic and on European glaciers. Unprecedented wildfires raged in the Arctic for the second consecutive month, devastating once pristine forests which used to absorb carbon dioxide and instead turning them into fiery sources of greenhouse gases. This is not science fiction. It is the reality of climate change. It is happening now and it will worsen in the future without urgent climate action,” Mr Taalas said.
“WMO expects that 2019 will be in the five top warmest years on record, and that 2015-2019 will be the warmest of any equivalent five-year period on record. Time is running out to reign in dangerous temperature increases with multiple impacts on our planet,” he said.
Such heatwaves are consistent with what we expect from climate change and rising global temperatures.
Belgium, Germany, Luxembourg, the Netherlands and the United Kingdom saw new national temperature records on 25 July, as weather maps were redrawn to include – for the first time – temperatures of above 40°C. Paris recorded its hottest day on record, with a temperature of 42.6 °C at 16:32, an unprecedented value since the beginning of measurements.
The heatwave was caused by warm air coming up from North Africa and Spain and this was then transported from Central Europe to Scandinavia, Norway saw new station records on 27 July, and 28 locations had “tropical nights” above 20°C. The Finnish capital Helsinki set a new station record of 33.2°C on 28 July and in the south of Finland, Porvoo saw a temperature of 33.7°C.
The anomalously high temperatures are expected to enhance melting of the Greenland ice sheet, which already saw an extensive melt episode between 11 and 20 June. The persistent high melt and runoff in the last few weeks means the season total is running near tothe 2012 record high loss, according to Polar climate scientists monitoring the Greenland ice sheet.
The station Nord, situated 900 kilometres from the North Pole, measured a temperature of 16°C and in western Greenland, the station of Qaarsut (near 71°N) recorded a temperature of 20.6°C on 30 July. At Summit Camp station, at the peak of the ice sheet and at an altitude of 3200m, a temperature of 0.0°C was measured.
“It is important to remember that that any given day or year, Greenland ice sheet surface mass budget is a result largely of weather, though with the background climate trend affecting this,” tweeted Ruth Mottram, a climate scientist with the Danish Meteorological Institute.
This will also impact Arctic sea ice, which where the loss of ice extent through the first half of July matched loss rates observed in 2012, the year which had the lowest September sea ice extent in the satellite record, according to the US National Snow and Ice Data Center.
The high temperatures also fanned wildfire activity in the Arctic, including in Greenland, Alaska and Siberia.
The Russian Federal Forestry Agency estimates that, as of 29 July, wildfires in Siberia have burned 33,200 square kilometres, with 745 active fires, causing massive ecological devastation and impacting air quality for hundreds of kilometres. The smoke can be clearly seen from space.
The European Centre for Medium-Range Weather Forecasts/Copernicus Atmosphere Monitoring Service estimated that July 2019 wildfire CO2 emissions for the Arctic Circle totalled 75.5047 megatonnes, which is comparable to the 2017 annual fossil fuel emissions of Colombia. This was more than double July 2018 levels, and followed a record month in June.
“By burning vegetation, the fires also reduce the capacity of the biosphere to absorb carbon dioxide. Action against climate change necessitates rather that we should expand this capacity,” said Oksana Tarasova, Chief of WMO’s Atmosphere and Environment Research Division.
The July heatwave follows an unusually early and exceptionally intense heatwave in June, which set new temperature records in Europe and ensured that the month of June was the hottest on record for the continent, with the average temperature of 2°C above normal.
June was also the warmest June on record globally.
In parts of Europe, the heat was accompanied by below-average precipitation. On 31 July, WMO’s regional climate monitoring centre for Europe, operated by the German Weather Service, or Deutscher Wetterdienst, updated its Climate Watch advisory on drought. This provides guidance to national meteorological and hydrological services in issuing climate advisories for their territory.
“A continuation of drought conditions and below-normal precipitation in large parts of Central and Northeastern Europe. In these areas mostly only 60-80 % of normal precipitation was recorded in June, in some parts even less.
There was also only scarce rainfall in July and forecasts show continued below-normal precipitation in most of the area with weekly deficits of partly 10-30mm for this week with a probability of 80% and higher,” it said.
In the wake of the heatwave, some European countries have faced very heavy precipitation, but it is not enough to undo the impact of drought conditions.
“Next week, above-normal precipitation will be expected over Central Europe, but this might not be sufficient to compensate for the rain deficits during the weeks before and therefore soils will be still dry. Northeastern Europe (Baltic countries and southern Finland) will still receive not more than below-normal to normal precipitation next week and therefore drought conditions are likely to continue.
Drought conditions can result in harvest losses, forest fires, lack of animal food water restrictions, restrictions of ship traffic due to low water levels,“ said the Deutscher Wetterdienst.
During the heatwave, national meteorological and hydrological services issued heat alerts - including the top-level red alert - and, in some areas, fire warnings to minimize the risk to life and the environment. Heat-health action plans mobilized civil protection efforts across the region.
Heat events kill thousands of people every year and often trigger secondary events such as wildfires and failures to electrical grids. Urbanization compounds the problem. Heat stroke, dehydration, cardiovascular and other temperature related diseases are major health risks.
The new absolute record of 42.6°C for Paris was recorded on 25 July at the centennial weather station in Paris-Montsouris, and broke the previous record dating back to 28 July 1947 with 40.4 °C. This temperature is typical of the average July temperature in Bagdad, Iraq. The night of 24/25 July was also exceptionally hot, with minimal temperatures above 25°C and even 28.3°C in a downtown Paris weather station. What is striking is the margin with which the records were beaten. Lille recorded 41.4°C, that’s nearly 4°C above the previous record. France set a new national temperature record of 46°C during the last heatwave on 28 June.
It was only the second time Météo-France has ever issued red level warnings for a heatwave in France. The first time was during June''s heatwave when several departments in the south were put on red alert. But it is unprecedented for Paris and the north of the country to be on a red alert for a heatwave. Thousands of hectares were burned by wildfires in northern France, where it is very unusual to see wildfires.
The Deutscher Wetterdienst described 25 July as “a day which will make weather history.” Germany set a new national temperature record (provisional figure) of 42.6°C in Lingen, near the Dutch border, defeating the old record by 2.3 °C. There were 25 weather stations above 40 °C. The previous national temperature record was 40.3°C (5 July 2015).
The Netherlands broke a 75-year-old heat record (set in Aug 1944) with a temperature of 40.7°C at Gilye Rijen. Belgium also set a new national record of 41.8°C. Luxembourg set a new national record of 40.8°C.
On 25 July, temperatures in the United Kingdom reached 38.7°C at Cambridge Botanical Gardens, the highest ever officially recorded, breaking the previous record of 38.5°C recorded in Faversham, Kent, in August 2003, according to the Met Office.
Climate change and heatwaves
“Such intense and widespread heatwaves carry the signature of man-made climate change. This is consistent with the scientific finding showing evidence of more frequent, drawn out and intense heat events as greenhouse gas concentrations lead to a rise in global temperatures,” according to Johannes Cullmann, Director of WMO’s Climate and Water Department. WMO will submit a five year report on the state of the climate 2015-2019 to the UN Climate Action Summit in September.
Many scientific studies have been conducted on the links between climate change and heatwaves.
Human-influenced climate change is likely to have added 1.5-3 ºC to the extreme temperatures recorded during Europe’s July 2019, according to a report by World Weather Attribution, which underlined the manifold risks.
“Heatwaves the height of summer pose a substantial risk to human health and are potentially lethal. This risk is aggravated by climate change, but also by other factors such as an aging population, urbanisation, changing social structures, and levels of preparedness. The full impact is only known after a few weeks when the mortality figures have been analysed.
Effective heat emergency plans, together with accurate weather forecasts such as those issued before this heatwave, reduce impacts and are becoming even more important in light of the rising risks,” it said.
“It is noteworthy that every heatwave analysed so far in Europe in recent years (2003, 2010, 2015, 2017, 2018, June 2019, this study) was found to be made much more likely and more intense due to human-induced climate change. How much more depends very strongly on the event definition: location, season, intensity and duration. The July 2019 heatwave was so extreme over continental Western Europe that the observed magnitudes would have been extremely unlikely without climate change,” it added.
In its In its Fifth Assessment Report, released in 2014, the Intergovernmental Panel on Climate Change said that “it is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century. It is likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.”
In its 2018 report on Global Warming of 1.5°C, the IPCC said that climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5 °C and increase further with 2 °C.
Limiting warming to 1.5°C rather than 2°C could result in 420 million fewer people being exposed to severe heatwaves, it said.
Between 2000 and 2016, the number of people exposed to heatwaves was estimated to have increased by around 125 million persons, as the average length of individual heatwaves was 0.37 days longer, compared to the period between 1986 and 2008, according to the World Health Organization.
Many countries have issued national climate assessments and scenarios which underline the close connection between climate change and heat.
For instance, the UK State of the Climate report showed an increase in higher maximum temperatures and longer warm spells. The hottest day of the year for the most recent decade (2008-2017) has increased by 0.8°C above the 1961-1990 average. Warm spells have also more than doubled in length – increasing from 5.3 days in 1961-90 to over 13 days in the most recent decade (2008-2017).
The summer of 2018 was the joint warmest on record for the UK as a whole and the hottest ever for England. The Met Office research showed that human-induced climate change made the 2018 record-breaking UK summer temperatures about 30 times more likely than it would have been naturally. By 2050 these are expected to happen every other year.
France has also reported an increase in the frequency and intensity of heatwaves over the past 30 years, according to Météo-France, in an observation echoed elsewhere in Europe.
Swiss climate change scenarios warn that if greenhouse gas emissions continue to increase, by the middle of this century, average summer temperatures may be up to 4.5 °C higher than now.
“The increases in the highest temperatures are even more pronounced than for the average seasonal temperatures. By 2060, the hottest days in an average summer could be up to 5.5 °C higher than they are today. This is explained in part by the fact that less water will be evaporating and cooling the ground because there will be less moisture in the soil,” says the Swiss report.
“The regions of Europe that surround the Mediterranean Sea, including Switzerland, are affected by some of the most severe increases in temperature extremes worldwide. This trend has been apparent even over recent decades and is very likely to continue into the future,” it says.
http://public.wmo.int/en/media/news/july-equalled-and-maybe-surpassed-hottest-month-recorded-history http://climatecentre.org/news/1177/wmo-says-july-a-rewrote-climate-historya http://www.un.org/en/climatechange/
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