Imperial experts express their hopes for a climate change deal in Paris

Negotiators discussing in Paris how to avert climate change have released a draft international agreement, but concerns remain among scientists.

A key topic being debated at the UN Climate Change Conference (COP21) is how much warmer to allow average global temperatures to rise, above a baseline temperature from before the pre-industrial period.

Any temperature rise will mean devastating increases in droughts, flooding, lack of access to clean water and degrading farmland.

However, low-lying states are particularly concerned that if average temperatures increase by more than 1.5°C, then the melting polar ice will mean they are submerged below rising sea levels.

Professor Sir Brian Hoskins, Chair of the Grantham Institute, Climate Change and the Environment:

"The target ceiling for warming in the agreement may be even lower than 2°C. However current country offers for greenhouse gas emissions are likely to exceed that by a degree. My concern is that the 5-year review process in the agreement must be robust and strong enough to make up the difference."

Dr Kaveh Madani, Senior Lecturer in Environmental Management in the Centre for Environmental Policy:

"Whether 1.5 or 2°C, the Paris negotiations can give us hope and valuable lessons. Common sense and threats can help nations unite even during times when radicals, terrorists, and Trumps are trying hard to divide the world."

"Concerns remain. History shows that we are good at setting ambitious targets and goals in major international summits. What matters more is how to get to the target. We get too busy negotiating over the targets that we forget that we need means to get to the end goal. 

"Whether 1.5 or 2°C, we should put more efforts into identifying feasible paths and processes to get us there. Otherwise, we are just adding more targets to our already ambitious agendas of sustainable development, eradication of poverty, proliferation of health and education, etc.

"It's easy to say and sign, what is hard is implementation. Often this is not the main concern of ambitious politicians who remain disconnected from science. 1.5 or even 2 degrees might not be feasible technically and scientifically, and ambitious and unrealistic goals will be quickly forgotten."

Prof Joanna Haigh, Professor of Atmospheric Physics and Co-Director of the Grantham Institute:

"The inclusion of a 1.5°C option in the draft agreement is remarkable, as is the ambitious proposed mitigation pathway of 70-95 per cent cuts by 2050 leading to zero carbon emissions by the latter half of the century.

"Showing the seriousness of this intention is the proposed request for the IPCC to produce a special report by 2018 on the potential climate impacts of a 1.5°C world. Perhaps some of these more ambitious options will not reach the final document but the fact that these targets are being seriously discussed is hugely positive."

Professor Sir Gordon Conway, Chair in International Development in the Centre for Environmental Policy: 

"The nexus between climate change and food security seems to have gained momentum in the Paris negotiations. It is very encouraging to see that a reference to achieving food security and to ending hunger is included in the draft text.

"It is absolutely crucial that in the last two days of the negotiations a final push is made to ensure that  global average temperature rise stays 'well below 2°C above pre-industrial levels' or 'below 1.5°C above pre-industrial levels'. Anything else would lead us into dangerous waters."