3.7 Extreme weather

Global warming entails more intense precipitation, more and longer heat waves and fewer extremely cold days and nights. In many regions we can observe increasing summer dryness. Severe droughts entail extreme wildfires, which in turn release huge amounts of carbon stored in forest grounds.

Long and severe droughts are in many cases interrupted by extreme precipitation and floods. Flood damage has increased substantially the last decades

The physics behind is fairly easy: a warmer global climate means a warmer troposphere. A warmer troposphere means more evaporation from land and sea. The warmer air can hold more water vapor before it condenses to rain.

Warmer troposphere and oceans in polar regions lead to more icebergs floating around but also polar sea ice cover melting combined with more precipitation usually in the form of snow; and more open seas for longer periods. This disturbs cloud patterns, jetstreams and the polar vortex with its circumpolar winds, in turn impacting on weather patterns in the temperate and polar zones. Polar Vortex: How the Jet Stream and Climate Change Bring on Cold Snaps

Low-lying coastal zones are particularly vulnerable through sea-level rise and changes in wave climate and stronger storms.

Studies suggest higher precipitation intensity for Northern Europe and increased dry-spell lengths for Southern Europe. High intensity and extreme precipitation are expected to become more frequent within the next 70 years. (Norwegian Meteorological Institute (2013) Extreme Weather Events in Europe: preparing for climate change adaptation)

More precipitation

It is important to remember that global warming means more evaporation from the oceans to the air. More moisture in the air means more precipitation. As long as the temperature remains below 0 ° C, this precipitation will be coming as snow. In North Western Europe and the North East of the USA, this means global warming causes more rain and more heavy, wet, potentially very damaging snowfalls, but gradually shorter winters.

Periods of heavy snow must be expected in the Nordic countries and parts of North America for several years ahead. The winter periods will become more erratic, with unusual mild periods in between cold periods. There will be more warm records than cold records. More icy roads for longer periods are likely.

Events

Heatwaves, droughts, mudslides

Wildfires

How Climate Change Ignites Wildfires From California to South Africa (May 2018)
82,000 Evacuated as ‘Once in a Lifetime’ Wildfire Shocks California (Aug 2016)
En trente ans, le réchauffement climatique a doublé les feux de forêt aux Etats-Unis
Western USA faces an explosion of wildfires. There is a “ brazen deception of the oil lobby and their Trump-inspired allies who deny science and fight every reasonable effort to curb global warming” (Jerry Brown, California’s governor, Sep 2016).
Wildfires are a climate change wake-up call (Aug 2017)
Wildfire in LA Burns 7,000 Acres During Record-Setting Heat Wave (Sept 2017)
Potent Mix of Record Heat and Dryness Fuels Wildfires Across the West.”These unprecedented extreme events are exactly the types of events that are more likely due to the global warming that’s already occurred.” (Sept 2017)
Oregon wildfire ravages picturesque gorge, ash chokes communities (Sept 2017)
California Fires: Record Hot Summer, Wet Winter Created Explosive Mix (Oct 2017)
Victims of California Mudslides Were Swept Away Weeks After Surviving Fires (Jan 2018)
Wildfires Rage Through Portugal and Spain, Kill at Least 39 (Oct 2017)
Wildfires to Hurricanes, 2017’s Year of Disasters Carried Climate Warnings (Dec 2017)
4 Questions on the California Fires and Climate Change (Dec 2017)
How California’s Fires Are Linked to Climate Chaos, Soil Health and Food Choices
Throughout history, agriculture has caused the loss of fertile soil, leading to the downfall of civilizations. (Jan 2018)
Wildfires rage in Arctic Circle as Sweden calls for help (July 2018)

New Scientist (2016) Canada’s huge wildfires may release carbon locked in permafrost
NYT (2016) Global Warming Cited as Wildfires Increase in Fragile Boreal Forest

Droughts

Floods

Desertification

New York Times (2016). Living in China´s Expanding Deserts
Feng, Q. et al. (2015). What Has Caused Desertification in China?
Luedi, J. (2016). China’s growing deserts a major political risk. Global Risk Insights,
Tao, W. (2016). Desertification and Land Degradation in China. International Soil and Water Conservation Research
The Telegraph. (2014). ‘Water war’ in Brazil as Rio’s supply threatened
Conflict on the Nile

Storms

Hurricanes and Climate Change
In 2020, Record-Breaking Hurricanes Arrived Early—and Often So far this season, 25 of 28 storms have been the earliest on record (Scientific American, 2020)

Increasing temperatures and risks

Royal Society Resilience to extreme weather
Are weather patterns changing because the Arctic is becoming warmer? (Munich re 2015)
Hansen, J. (2016) Ice Melt, Sea Level Rise and Superstorms Video Abstract
Hansen, J. (2016) Ice Melt, Sea Level Rise and Superstorms: The Threat of Irreparable Harm – Transcript
Climate Change + Population Growth + Economic Expansion = More Severe Flooding
NASA: Applied Remote Sensing Training (ARSET)
We are living in the planet’s most unusually warm period in modern history (May 2016)
Dietz, S. & Stern, M. (2014) Endogenous growth, convexity of damages and climate risk (Grantham work paper)
Soaring Temperatures Will Make It Too Hot to Work, UN Warns (July 2016) (Bloomberg)
National Academic Press (2016) Attribution of Extreme Weather Events in the Context of Climate Change (Downloadable book)
Climate change is triple risk to Europe (Aug 2017)
Extreme weather events (and the costs) are piling up. When you tally it all up, the costs are likely to end up at three quarters of a trillion dollars or more. And that’s just for this decade.
Global Warming Is Messing with the Jet Stream. That Means More Extreme Weather.
Munich re: NAT CATS 2014: What’s going on with the weather?
Does global warming mean more or less snow?
American Meteorological Society (2016) Explaining Extreme Events from a Climate Perspective
Extreme weather events on the rise, European scientists warn (2018)
Norge fra 1900 til i dag -Vær og klima i Norge har variert stort i gjennom historien
Making sense of future climate (CICERO, Jan 2017)
Drastic cooling in North Atlantic beyond worst fears, scientists warn (Feb 2017)
The Science Linking Arctic Warming to This Crazy-Cold Winter (MIT, 2018)
‘Crazy, Crazy Stuff’: Arctic Winter Warmest on Record. The Arctic just experienced its warmest winter on record, scientists say. In the dead of winter, temperatures at the North Pole approached the melting point, (March 2018)
2017 Weather and Climate Disasters Cost U.S. Record $306 Billion. 2017 was the third warmest year since record-keeping began in 1895 (Jan 2018)

Insurance

NASA: Quiz weather extremes

Home	Chapter 3	3. Impacts
		3.1 More water vapor
		3.2 Sea level rise
		3.3 Polar sea ice
		3.4 Air pollution
		3.5 Acidification
		3.6 Health
		3.7 Extreme weather
		3.8 Economy
		3.9 Refugees and conflicts
		3.10 Glaciers
		3.11 Tipping points
		3.12 Biodiversity
		3.13 Water

	Chapter 4	4. Ecosystems