Extreme events on the increase in a changing climate

Earlier this month, Professor Peter Stott examined extreme weather events worldwide and how attribution studies can assess whether these are the result of anthropogenic (human-induced) climate change. But what does the future hold? Can we expect to see more extreme events? Here we explore what science tells us about droughts, heat, wildfires, and rains/floods.

Rainfall/Flooding

We mentioned in our previous blog post that an attribution analysis of the UK’s wettest February on record (occurring in 2020) showed that extreme rainfall experienced could become nine times more likely by the end of the century than in pre-industrial times.[1]. Wet weather events like these are expected to increase in the coming decades in the UK.

The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that “it is virtually certain that, in the long term, global precipitation will increase with the increase in global mean surface temperature.” Warmer air holds more moisture, which is one reason rising global temperatures will cause more precipitation in some regions of the world. Particularly high levels of precipitation may occur due to slow-moving storms, and the potential accumulation of high precipitation is projected to be 14 times more frequent across Europe by 2100 (for global warming of 4.3°C, an emissions scenario elevated)[2].

Natural variability, particularly in places like the UK, can make it more difficult to separate the contribution of anthropogenic climate change from other influences in heavy rainfall events than extreme temperatures. It is not yet possible to discern underlying changes in local precipitation extremes above natural variability using the observational record alone.[3]. However, research following the record rainfall in October 2020 has indicated that days with extreme rainfall accumulations will become more frequent throughout the century.[4].

Heat

In the UK and around the world, recent years have seen a series of record temperatures. In June 2021, Canada reached its hottest recorded temperature of 49.6°C (you can learn more about this in our latest MostlyClimate podcast with a guest speaker from Environment and Climate Change Canada) and Australia recorded its hottest day on record in January of this year. year with 50.7°C.

In the UK, we can expect to see hotter and drier summers in the future, with temperatures similar to the hottest summer on record in 2018, around 50% more likely by 2050, even in a low emissions scenario.[5]. A study following the UK’s highest recorded temperature (38.7°C in July 2019) considered whether exceeding 40°C is within the capabilities of UK climate[6]. Lead author, Met Office Senior Scientist Dr Nikolaos Christidis, concluded that “the probability of exceeding 40°C anywhere in the UK in any given year has increased rapidly and, without curbing greenhouse gas emissions, greenhouse effect, these extremes could be occurring.” every few years in the climate of 2100.”

If the average global temperature rises 2°C above pre-industrial levels, the number of people in regions around the world affected by extreme heat stress – a potentially fatal combination of heat and humidity – could increase nearly 15-fold. The new interactive atlas from the Intergovernmental Panel on Climate Change (IPCC), showing possible climate futures for temperature and precipitation, highlights the importance of minimizing future global warming.

forest fires

Bushfires are often linked to significant drought in the UK. Increased temperatures and reduced humidity[7] are likely to lead to an increased risk of fire danger in the UK by the end of the century if temperatures do not stay below 2°C and even at this level of warming the risk could double[8].

A recent report by the United Nations Environment Program has predicted that even if greenhouse gases are reduced, there could be a global increase in extreme wildfires of up to 50% by the end of the century. The report, which included contributions from the UK Met Office and Center for Ecology and Hydrology, found that some of the biggest increases will be in areas not normally used to seeing wildfires, such as the Arctic and central Europe. Tropical forest areas in Indonesia and the southern Amazon are also likely to see increased burning if greenhouse gas emissions continue at current rates.

Research published on the Amazon rainforest last year found that a shift to hotter, drier conditions in the future could result in more area burned and resulting fire emissions. The Amazon rainforest is a natural carbon sink, removing and storing carbon from the atmosphere. With global warming limited to 1.5°C above pre-industrial levels, climate model experiments show a 7% reduction in carbon storage. However, if warming were to increase to 4°C, the loss of carbon storage from these ecosystems could reach 30%, highlighting the importance of understanding the link between climate change, fire risk and the carbon cycle that could be used to inform fire management and land use strategies.

droughts

2010-2012 saw an exceptional drought in the UK, one of the most significant for some regions of England in 100 years[9]. Research published last year using UKCP18 data indicated more frequent and severe long-term droughts in the UK, with droughts at least as severe as that experienced in 2010 increasing by 86% at global warming level 2 .0 °C and 146% at 4.0 °C. The graph below also shows how summers are expected to become drier relative to typical conditions in southern and northern Europe between now and 2100, with drier summers in the south.[10].

A climate risk report completed earlier this year for the East Africa region indicates that a projected increase in seasonal rainfall variability could result in wetter and drier years more frequently and increased risk of floods and droughts. These have the potential to impact socioeconomic development by affecting sectors such as agriculture, electricity generation, and health.

Take steps to minimize impacts

As explored earlier this month, we are already seeing an increase in extreme events attributable to climate change. Climate projections clearly indicate that we can expect further increases in many of these in the coming decades, both in the UK and around the world. Limiting carbon emissions to minimize future warming can help avoid the worst of these impacts, which is why the 2021 Glasgow Climate Pact recognized the imperative to “keep 1.5°C alive” and ensure that global temperatures do not exceed this level. To combat the effects of these extreme events, we will also need to adapt to our changing climate, recognizing that we are already seeing impacts, and that even if we stopped all carbon emissions today, we would see impacts from climate change long after. the future.

We have been sharing information about extreme events on our social media channels this month. Follow #GetClimateReady to learn more and keep an eye out for a focus on mitigation soon.


[1] Davies et al 2021 https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.3955

[2] Kahraman et al 2021 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL092361

[3] Kendon et al 2018 https://journals.ametsoc.org/view/journals/clim/31/7/jcli-d-17-0435.1.xml

[4] Christidis et al. 2021 https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl.1033

[5] United KingdomCP18

[6] Christidis et al 2020 https://www.nature.com/articles/s41467-020-16834-0

[7] Arnell et al https://centaur.reading.ac.uk/96625/8/Arnell_2021_Environ._Res._Lett._16_044027.pdf

[8] Perry et al https://nhess.copernicus.org/articles/22/559/2022/nhess-22-559-2022-discussion.html

[9] Kendon et al https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.2101

[10] https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2021/drier-european-summers-projected-under-human-duced-climate-change

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