In September 2019, I wrote a blog for the EGU Cryosphere blog series which focused on the extreme weather events in summer 2019. I spoke of wildfires in the Arctic, extreme melting of the Greenland Ice Sheet and melting sea ice (I am sure many can remember the picture of dogs pulling a sledge across bright blue water instead of white ice). When I wrote that piece, I assumed that I wouldn’t be writing about extreme seasons for a few more years. After all, the nature of extremes is that they don’t occur all of the time. Oh how wrong I was. Enter stage left: 2020.
The year 2020 will be remembered by most as the year that the coronavirus took hold and we spent most of our time indoors and separated from loved ones. But this blog post will focus on the extreme weather conditions which happened alongside COVID-19. From January 1st 2020 to December 31st 2020, many extreme or wild weather events took place. Here is a look back at just some of them.
The 2020 Atlantic Hurricane Season
On an average year, the Atlantic ocean sees approximately 12 named storms (once storms become sufficiently strong or large, they are named and listed) and 6 hurricanes, of which 3 are considered ‘major’. The 2020 hurricane season recorded 30 storms (they even had to switch from the English to Greek alphabets, as they were running out of names), 13 hurricanes and 7 major hurricanes.
Many of the hurricanes made landfall in Central and Northern America, causing widespread flooding, intense rainfall and wind damage. Over 400 people died in the 2020 hurricane season and almost every hurricane caused losses of over a billion dollars (disasterphilanthorpy.org).
Research is ongoing to identify how climate change has and will impact hurricanes. Warmer oceans will likely cause an increase in the intensity (Mudd et al. 2014) and frequency of strong hurricanes (Holland and Bruyère, 2013) whilst increased water capacity of the atmosphere (a warmer atmosphere can hold more moisture according to the Clausius-Clapeyron theory) will cause more rainfall during hurricanes (Keelings and Hernández Ayala, 2019). Furthermore, higher sea levels will likely cause more coastal flooding associated with the tidal surge of hurricanes (Lin et al. 2012).
Wildfires across the globe
2020 started as it meant to go on, with wildfires ravaging Australia. Throughout the austral summer of 2019-2020 (December to February), wildfires spread quickly throughout many states, especially in the south. Whilst wildfires are a natural occurrence, they have been larger and more frequent in recent years, both in Australia and beyond. In Australia specifically, three years of drought, including three very dry winters (King et al. 2019) led to the fast spread of fires. There were many disturbing images in the media in early 2020, of firefighters trapped in trucks and communities fleeing to the beach and ocean to escape the fires.
Humans were not the only species affected by the wildfires however. Koala bears in Australia and migrating birds over the west coast of North America suffered injury and death due to the fires. Further north, wildfires burned through large parts of the Arctic. That’s right… the Arctic was on fire again and earlier than ever before. Starting in May (July is the usual start of the wildfire season at this location), parts of Siberia set alight (Witzer, 2020). Fires also burned further north than before and in regions previously ice covered. The additional issue with wildfires in the Arctic is the burning of peat. Unlike in mid-latitudes, where forest fires are common, peat burning in the Arctic does not grow back, meaning the carbon is permanently lost (Witzer, 2020).
Sea ice; second lowest on record
It seems like every year we are breaking or nearing records for sea ice loss. On September 15th 2020, sea ice extent reached the second lowest on record (after 2012) (NASA, 2020). The high melt season started early after a Siberian heat wave in spring prompted early melt onset. Increasing sea ice melt, year after year, means now even thicker ice floes are disappearing, and there is very little multi-year sea ice left. The ice is therefore shrinking in area and thickness.
Drought and heatwaves
Even in areas without wildfires, droughts are becoming more frequent. In Zimbabwe, groundwater is becoming rapidly scarce thanks to year after year without adequate rainfall, and drought conditions since 2018. Across many parts of Africa, droughts are becoming more frequent and intense (EOS, 2018). Rainfall in Zimbabwe is set to decline due to climate change by 5-18% by 2100 (EOS, 2020), so drought conditions are unlikely to let up. Over 38% of Zimbabwe’s population rely on groundwater, including farmers, which means many people are affected by droughts which have occurred regularly since 1992 (EOS, 2020).
Drought in Southeast Asia in spring 2020 led to the first billion-dollar drought on Earth. Meanwhile, April heat records were smashed in Kyrgyzstan (35.1°C), China (43.5°C) and Mongolia (36.0°C), with temperatures more like July values (wunderground, 2020). North Korea and Japan also observed new heat records in May, with many places recording temperatures above 40°C! In summer, Thailand declared a state of emergency due to salt water intruding into fresh water aquifers due to the lack of precipitation (wunderground, 2020).
Looking forward to 2021
So looking forward to 2021, will this year be as extreme? Extreme conditions are hard to predict, but there are some indications that the hurricane season will be above average, and wildfires are expected across large parts of the midwest of USA. Unless drastic reductions to our greenhouse gas emissions happen over the next decade, we should expect to see more extreme conditions in the future.