The Earth’s average temperature has increased by about 1 degree C since pre-industrial times, which for the climate record is calculated as the period 1850-1900.
Although this is an average, some regions are experiencing a much faster rate of warming. Nowhere is this more apparent than parts of the Arctic, where melting sea ice is creating areas where heat from the sun is absorbed by darker ocean water, rather than being reflected back into space by highly reflective sea ice. This process is a key contributor to Arctic amplification of the warming rate and is an expected consequence of climate change. However, this is only part of the story.
Parts of northern Eurasia have been experiencing extremely high temperatures this year. Monthly average temperatures were more than 10.0 C above average in some places, due to a combination of climate change and extreme climate variability.
The extra heat can be traced back to the record high Indian Ocean Dipole in late autumn 2019. This led to a strong winter jet stream leading to extreme late winter warmth over Eurasia and a supercharged stratospheric polar vortex leading to persistence into spring. Once the higher than normal temperatures were established reduced ice and snow only exacerbate the warmth.
This record-breaking heat in northern Eurasia has helped to propel monthly global temperatures and has fuelled media headlines about 2020 being on track to be the warmest year on record globally. But is that going to be the case?
Whilst there have been some record months, this year, overall 2020 is still not running at record temperature compared to 2016 – the warmest year for global average surface temperature. Prof Adam Scaife is the Head of Met Office Long Range Prediction. He said:“We are likely to have seen the most extreme global temperatures already this year as La Niña is now developing and the final value is likely to fall back into our forecast range of 0.99 to 1.23 C”. So while 2020 is running very high, there is no guarantee of a record this year.
Note: The global forecast for 2020 was produced in December 2019.