Professor James Renwick, Victoria University of Wellington, comments on new findings that show 2014 ranks as Earth’s hottest on record since 1880.
We are only a few weeks past the warmest year on record but it is now 104 years since the last coldest year on record. The year 1988 was a record warm one at the time, and spurred a lot of interest in ‘global warming’ in the late 1980s, but now 1988 doesn’t even feature in the top 20 warmest years.
Temperatures in individual years vary for many reasons, but the overall trend is upwards. Only greenhouse gas increase can account for the warming we’ve seen, especially since the middle of the 20th century.
Temperatures in different regions can also vary for many reasons, as heat is shunted around by natural factors such as El Nino, or major ocean currents. So while 2014 was the warmest on record overall, averaged across the globe, some places (such as the eastern United States of America) were cooler than normal last year. Meanwhile, western Europe had its warmest year in centuries. New Zealand was warmer than normal in 2014, but was not as warm as 2013. This was partly due to a tendency towards more cool southerly winds than normal in the New Zealand region, and the ameliorating influence of the southern oceans.
This year (2015) has started off warm and dry in many parts of the country. Whether or not this comes out as another record-breaker, here or globally, remains to be seen. What we can be sure of is that unless we take action to reduce greenhouse gas levels, we will continue to see new record warmth into the future, along with increasingly extreme heatwaves and rainfalls.
