- According to recent study, earth is at the risk of entering an irreversible hothouse condition – where the global temperatures will rise by four to five degrees even if targets under 2015 Paris climate deal are met.
- Hothouse Earth climate will in long-term stabilise at global average of 4-5 degrees Celsius higher than pre-industrial temperatures with sea level 10-60 metres higher than today.
Key Highlights of Study
- Currently, global average temperatures are just over 1 degree Celsius above pre-industrial and rising at 0.17 degree Celsius per decade.
- Keeping global warming to within 1.5-2 degrees Celsius as agreed in 2015 Paris climate agreement by around 200 countries may be more difficult than previously assessed.
- Human-induced global warming of two degrees Celsius may trigger other Earth system processes often called feedbacks that can drive further warming even if greenhouse gases emissions are stopped.
- Avoiding this scenario will require redirection of human actions from exploitation to stewardship of Earth system.
- The study consider ten natural feedback processes, some of which are tipping elements that lead to abrupt change if critical threshold is crossed.
- These feedbacks can turn from being friend that stores carbon to foe that emits it uncontrollably in warmer world.
- These feedbacks include
- Permafrost thaw,
- Weakening land and ocean carbon sinks,
- Loss of methane hydrates from ocean floor,
- Increasing bacterial respiration in oceans,
- Boreal forest dieback,
- Amazon rainforest dieback,
- Reduction of northern hemisphere snow cover,
- Loss of Arctic summer sea ice and reduction of Antarctic sea ice and polar ice sheets.
- These feedbacks tipping elements can potentially act like row of dominoes. Once one is pushed over, it pushes Earth towards another.