Down To Earth | January 16, 2020
Expect a slew of extreme weather events in 2020, continuing the trend from past two years.
“2020 has started out where 2019 left off — with high impact weather and climate related events,” World Meteorological Organisation (WMO) Secretary-General Petteri Taalas said.
Australia had its hottest, driest year on record in 2019. This set the scene for massive bushfires that devastated people and property, wildlife, ecosystems and the environment, he pointed out.
Record levels of heat-trapping gases in the atmosphere will make the weather more extreme in the coming decades, he warned.
The World Meteorological Organization (WMO) has said 2019 was the second-warmest year ever recorded.
After analysing five different datasets, scientists declared that average temperature for 2019 was 1.1 degree Celsius above the average for pe-industrial 1850-1900. The datasets ranged from 1.05-1.2°C warming.
WMO declared that 2010-2019 was the warmest decade ever. It included the five warmest years since records started being kept in 1850. The warmest year ever recorded was 2016 that also saw a very strong El Niño event, usually associated with warmer temperatures across the world in general.
The El Niño Southern Oscillation (ENSO) is a natural phenomenon comprising a warm and a cold phase — El Niño and La Niña, respectively. The period when both are absent is called ‘ENSO-neutral’.
During El Niño, central and equatorial Pacific Ocean become unusually warm. This disrupts global wind patterns, affecting climatic conditions in tropical areas like Africa, sub-tropical areas like India and extra-tropical areas like North America.
In India this often, but not always, causes erratic monsoons, floods and droughts.
The first half of 2019 experienced weak El Niño conditions. Once the El Nino conditions abated, southwest monsoon picked up to record levels, flooding many parts. Nearly 2,000 people died.
The season’s total rainfall was 109 per cent of the long-period average and withdrew only in mid-October. At the same time, the India Meteorological Department (IMD)said it was the warmest since 1901, when records start.
Temperatures around the world, especially on the oceans, were warmer than usual even after the El Niño conditions abated in July. The WMO linked this to the emission of greenhouse gases (GHGs) from human activities and resulting climate change.
Levels of GHGs also reached record levels in 2019. In November, the WMO declared that the GHG in the atmosphere was at the highest in three million years.
The year also recorded the highest ocean heat, according to a January 13, 2020 paper in the journal Advances in Atmospheric Sciences.
The WMO considers ocean heat content a good way to quantify global warming as 90 per cent excess heat in the atmosphere is stored within the world’s oceans. “The past five years are the top five warmest years in the ocean historically with modern instruments, and the past 10 years are also the top 10 years on record,” the WMO said.
There were a record number of tropical cyclones in the Indian Ocean region post-monsoon, indicating warmer sea surface temperatures. These are needed for the genesis of cyclones.
There were five cyclones in 2019 on the Arabian Sea, which usually experiences only one cyclone a year. Out of the five, two were very severe cyclonic storms, one extremely severe cyclonic storm and one super cyclonic storm, according to IMD.
The trends of a record-breaking 2019 are crossing over into 2020; the imprint of climate change on world weather conditions and extreme weather events has never been clearer.