2°C to 1.5°C: How half a degree will impact the future?

The Paris Climate Conference last December, set the highly ambitious and universal long-term global goal to keep warming not just “well below 2°C” but also “to pursue efforts” to limit the average world temperature rise to 1.5°C above pre-industrial (late 19th century) levels. Raising the critical question: How dramatic the impacts will be for an additional half degree rise? And, who will face the consequences?

As we are already one degree above the pre-industrial levels, we can see the significant climate impacts all over the globe; resulting in sea-level rise, salinity of river water, intense heat waves and unpredictable weather fluctuations and higher precipitation rate. It is foreseeable that limiting the global temperature rise to 1.5°C will be twice as hard as keeping it below 2°C if not more. The Paris Agreement (PA) is often considered as the hard earned “ray of hope” for The Least Developed Countries (LDCs) and the Small Island Development States (SIDS) as they are most vulnerable to climate change. Therefore, Bangladesh, a member of the LDCs has welcomed the historical PA as a climate action for a better future. So how essential is it for a country like Bangladesh? Is it worth pushing for?

Photo Courtesy: NASA Website
Photo Courtesy: NASA Website

In Paris, delegates called on the U.N.’s Intergovernmental Panel on Climate Change (IPCC) to report on the implications of a 1.5°C target by the year 2018. The report will demonstrate improved policies on more strict emission pathway to achieve the target. So what it would be like in both 2°C and 1.5°C?

The comprehensive assessment of the differences in impacts between 1.5°C and 2C, undertaken as part of the review of the long-term global goal of the UNFCCC concludes that a 2C cannot be a safer limit for warming. It is only now that the scientists have started to describe how a world with 1.5°C warming would look like. Research published this April in Earth System Dynamics analyzed the climate models used in IPCC’s Fifth Assessment Report, where they considered 11 different indicators including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise to project impacts at 1.5°C and 2°C warming at the regional level. According to the study’s lead author Carl-Friedrich Schleussner, they found “Significant differences” for all the impacts like inundation (due to sea- level rise and glacier melting), unavailability of fresh water, issue of food security, unbearable heat waves in summer and unpredictable precipitation rate. The impacts are projected to be more severe and pervasive for the countries already spotted as most vulnerable to climate change.

Bangladesh is identified as one of the six most affected areas in the world by this year’s Global Climate Risk Index (CRI). So, the country is anticipated to face extreme events like, rising sea-levels, intense tropical cyclones, drought and floods and extreme heat waves by the end of this century. A fifth of Bangladesh consists of low-lying coastal zones where the land is typically 10 meter above the sea-levels. It is predicted that even a meter increase in the sea-level may cause a loss of 16% of the country’s low-lying areas under water, making around 30 million people homeless. Earth System Dynamics assessed that by 2100, sea-level will rise about 50 cm in a 2°C warmer state, which is 10 cm more than what it would be if global average temperature rises to 1.5°C. Schleussner also stated that the “sea level rise will slow down” during the 21st century only in the 1.5°C scenario.

The consequences of global warming is evident in Bangladesh, last summer the country recorded its highest temperature of 42.4°C in 54 years. If earth’s average temperature upsurge the summer seasons will prolong from 1.5 to 3 months globally at 2°C rise. Also it is anticipated that increase in heavy precipitation intensity due to warming; will affect the high latitude (>45°N) and monsoon regions (Bangladesh is a tropical monsoon region) most; i.e. wet countries will become wetter and dry countries drier. Schleussner and others showed in the research how South Asia (in which Bangladesh belongs to) alone will face 10% increase in heavy precipitation intensity in 2°C warmer world and a much less severe increase of 7% in 1.5°C setting.

William Hare, a senior scientist and CEO at Climate Analytics who also took part in the Earth System Dynamics research stated that the biggest rise in impacts between 1.5°C and 2°C – will be faced by highly vulnerable countries to climate change. The Paris Agreement goes into effect only when 55 nations (the rich and developed ones), accounting for at least 55 percent of total global greenhouse-gas emissions, ratify it. With the announcement of ratification of the Paris Agreement by the United States and China, the world’s two biggest economies and biggest emitters of greenhouse gases, it opens a new window of “opportunities’ to the pathway of achieving the global long-term temperature goal of 1.5°C.

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Shaila Mahmud is a Visiting Researcher focusing on Climate Change Adaptation, Loss and Damage and Climate Finance at International Centre for Climate Change and Development (ICCCAD)


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