This week, representatives from 197 parties who signed the Paris Agreement are meeting at Marrakech for the 22nd Conference of Parties (COP22).
The central focus of the Paris Agreement is to strengthen the global initiatives to keep the rise of temperature, by the end of this century, well below 2 degrees Celsius above pre-industrial levels and pursue efforts to limit it even further to 1.5C.
Therefore, it is important to understand why the rise of temperature of an additional one and a half degrees matters.
What types of measures are required to achieve these targets? What are the additional benefits of limiting the global warming level below 1.5C compared to 2C?
As a research scientist working in this field, I have made an attempt to explain these issues based on the available scientific information.
How realistic is the goal?
Limiting the warming level below 1.5C is still feasible. Based on the climate projections of low emission scenarios, a few models show that the warming level will peak at 1.5C by mid-century before slowly declining below this level.
However, it will require aggressive mitigation actions beyond the Intended Nationally Deterministic Contributions (INDCs) that all countries of United Nations Framework Convention on Climate Change (UNFCCC) are currently planning.
Possible measures
Every country should follow a pathway of sustainable low carbon emission energy.
Green energy consists of energy conservation, sustainable energy, and sustainable transport of energy.
Energy conservation includes efficient energy use, green buildings, heat pump, and low-carbon power, etc.
Sustainable energy includes renewable energy such as hydro-power, solar energy, wind energy, geo-thermal energy, bio-energy, and tidal energy. Sustainable transport includes carbon-neutral fuel, electric vehicles, fossil fuel phase-out, green vehicle plug-in hybrid, etc.
Additionally, research is on-going to achieve net zero emission by the end of this century.
Programs like Reducing Emissions from Deforestation and Forest Degradation (REDD) and bio-energy can help to attain a greener future.
Bio-energy with carbon capture and storage (BECCS) is a future greenhouse gas mitigation technology, which produces negative carbon dioxide emissions by combining bio-energy (energy from bio-mass) use with geologic carbon capture and storage.
Tropical coral reefs, which are already under stress due to high ocean temperature, would get a chance for adapting under 1.5C. However, tropical corals will be virtually wiped out by 2100 in a 2C increase
For example, a recent study showed that algae or cyanobacteria offer a natural mechanism to convert solar energy into a fuel.
Is focus on the 1.5C goal a distraction from the 2C goal?
Not really. The world will be safer if we are able to keep global increase of temperature well below 1.5C from the pre-industrial period.
The Paris Agreement aims to make the efforts to limit the temperature increase to 1.5C, by recognising the need to avoid the risks and irreversible negative impacts of climate change.
Climate vulnerable countries such as the least developed countries (like Bangladesh) and the small islands would suffer much less -- if we are able to limit temperature increase below 1.5C.
The difference between 1.5C and 2C
Many studies are on-going to detect the difference in adverse impacts between the temperature increase of 1.5C and 2C.
A recent study of Oxford University revealed that the probability of extreme events like floods, droughts, storms, and heat-waves would be increased with a 2C increase in temperature.
Tropical coral reefs, which are already under stress due to high ocean temperature, would get a chance for adapting under 1.5C.
However, tropical corals will be virtually wiped out by 2100 in a 2C increase. Extra half a degree would reduce 50% of the corn yields in some parts of Africa.
Warming below 1.5C would save the Amazon rainforest and the Siberian tundra from melting and releasing dangerous methane. By the end of this century, the sea-level rise would be an additional 10cm between a 1.5C and a 2C temperature increase. Sea-level rise is already threatening many small island countries and flat deltas like Bangladesh.
For many regions of the Mediterranean, which are suffering from drought, the availability of fresh-water resources would be about 10% lower in a 1.5C increase compared to 17% lower in a 2C increase.
Therefore, it is clear that tropical regions which are known to be mostly in developing countries are already highly vulnerable to climate change and will face the biggest challenges if global warming rises above 1.5C.
Finally, I can tell you that climate change is a threat which follows nothing but the law of physics. It is time that we stood up to save our planet and our humanity.
AKM Saiful Islam is a Professor of the Institute of Water and Flood Management at the Bangladesh University of Engineering and Technology.
