The evidence of climate change

The evidence of climate change

(Image: Steffen M. Olsen, Danish Meteorological Institute, Greenland 2019)

Dangerous tipping points

Summary

Fig. 1 (Image: Rosamund Pearce/Tom Prater for Carbon Brief)

Overview

“It’s a nasty shock that tipping points we thought might happen well into the future are already underway.” –  Professor Timothy Lenton interview in Phys.org following his co-authored paper in Nature, 2019.

The implications for tipping points are so complex and widespread that only two intertwined tipping points with the most obvious physical impacts on New Zealand are currently outlined on this website:

  1. The melting cryosphere: Arctic sea ice, Greenland, permafrost, (eg Fig. 2) and Antarctica: leading to accelerated rising sea levels, more extreme weather events, loss of critical ecosystem services (biodiversity), social and economic impacts
  2. Changes in ocean currents: leading to extreme weather events, loss of critical ecosystem services (biodiversity), social, and economic impacts

“In New Zealand, 72,000 people are currently exposed to present-day extreme coastal flooding, along with about 50,000 buildings worth $12.5 billion. The risk exposure increases markedly with sea-level rise, particularly during the first metre of rise…. There is near certainty that the sea will rise 20-30cm by 2040.” – NIWA, 2019

The other tipping points in Fig. 1 will also have some physical impacts as well as global economic and social impacts outside the scope of this website. For further information about these tipping points, see Carbon Brief’s website (Fig. 1) and the free to access paper in Nature (published Nov. 2019; updated April 2020). 

Video 1: Professor Timothy Lenton, Director Global Systems Institute, briefly explains climate tipping points

Fig. 2: Russian Arctic heat map shows air temperatures up to 45°C in some places 19 June 2020. The heat has been linked to thawing permafrost, widespread wildfires, and swarms of tree-eating moths in the region. (Image: European Union, Copernicus Sentinel-3)

Video 1: Steffen M. Olsen, Danish Meteorological Institute. The ice sheet near Qaanaaq Greenland that they would normally sled across is covered in vast meltwater lakes due to extreme surface warming (17°C) in June 2019. Meltwater eventually drains into the ocean, contributing to rising sea levels and disrupting oceanic currents.

References and further reading