Global Warming Current Affairs

Earth at risk of becoming irreversible hothouse: Study

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.

Month: Categories: Environment Current Affairs 2018

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Global warming driving harmful algae growth: Study

Scientists have found that global warming is driving proliferation of Noctiluca algae (commonly known as sea tinkle), a harmful algae in Arabian Sea responsible for glowing of Mumbai’s beaches in dark. The study was jointly conducted by researchers from Indian National Centre for Ocean Information Services (INCOIS), a Ministry of Earth Sciences body and US National Oceanic and Atmospheric Administration (NOAA).

Key Facts

Noctiluca algae is parasite and occurs in patches or blooms in northern Arabian Sea. Its bioluminescence characteristic i.e. glow in dark has earned it name ‘sea sparkle’. The algae compete with fish for food and choke their supply. It devours one of most important planktonic organisms at base of fish-food chain, namely diatoms. It also excretes large amounts of ammonia, which causes massive fish mortality.

Significance of study

Earlier studies had linked increase in algal patches to coastal pollution from major Indian cities along west coast. However, in this study researchers found that global warming conditions are responsible their proliferation. Warming of oceans due to global is increasing temperature differences among layers of sea water.

This temperature differences has slowed the upward transport of nutrients like silicate from ocean bottom, lowering its concentration at surface. Diatoms growing in surface water which need both sunlight and silicate to build their glass skeletons, fail to thrive when silicate is in short supply. On other hand, Noctiluca algae remain unaffected by these changes and prey on remaining diatoms. Thus, the study shows that intensifying global warming conditions will disrupt fish-food chain and cause decline of fisheries in the region.

Month: Categories: Environment Current Affairs 2018

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