How half a degree will impact the future? | The Daily Star
12:00 AM, September 10, 2016 / LAST MODIFIED: 10:49 PM, October 08, 2016

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 degree Celsius” but also “to pursue efforts” to limit the average world temperature rise to 1.5 degree Celsius above pre-industrial (late 19th century) levels. This raises the critical question: How dramatic will the impacts 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: 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 degree Celsius will be twice as hard as keeping it below 2 degree Celsius 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?

In Paris, delegates called on the UN's Intergovernmental Panel on Climate Change (IPCC) to report on the implications of a 1.5 degree Celsius 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 degree Celsius and 1.5 degree Celsius?

The comprehensive assessment of the differences in impacts between 1.5 degree Celsius and 2 degree Celsius, undertaken as part of the review of the long – term global goal of the UNFCCC concludes that a 2 degree Celsius cannot be a safer limit for warming. It is only now that the scientists have started to describe how a world with 1.5 degree Celsius warming would look like. Research published this April in Earth System Dynamics analysed 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 degree Celsius and 2 degree Celsius warming at the regional level. According to the study's lead author Carl-Friedrich Schleussner, they found “significant differences” in all the impacts including 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 sea-level may cause a loss of 16 percent of the country's low-lying areas under water, making around 30 million people homeless. Earth System Dynamics assessed that by 2100 sea-levels will rise about 50cm in a 2 degree Celsius warmer state, which is 10cm more than what it would be if global average temperature rises by 1.5 degree Celsius. Schleussner also stated that the “sea level rise will slow down” during the 21st century only in the 1.5 degree Celsius scenario.

The consequences of global warming are evident in Bangladesh. Last summer, the country recorded its highest temperature of 42.4 degree Celsius in 54 years. If earth's average temperature upsurge is at 2 degree Celsius rise, the summer seasons will prolong from 1.5 to 3 months globally. Also increase in heavy precipitation intensity is anticipated due to warming; it 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) alone will face 10 percent increase in heavy precipitation intensity in a 2 degree Celsius warmer world and a much less severe increase of 7 percent in a 1.5 degree Celsius setting.

William Hare, a senior scientist and CEO at Climate Analytics who also took part in the Earth System Dynamics research stated that highly vulnerable countries to climate change would face the most severe of impacts for temperature rises between 1.5 degree Celsius and 2 degree Celsius. 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 rise goal of 1.5 degree Celsius.

The writer is a Visiting Researcher at International Centre for Climate Change and Development (ICCCAD).

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