A strategy for achieving net zero emissions by 2050: Written evidence by Dr Jennifer L. Castle and Prof Sir David F. Hendry to the House of Commons Public Accounts Committee

Abstract:

Climate change will continue until the target of net zero greenhouse gas (GHG) emissions is achieved. The benefits of starting now seem likely to far exceed the costs of tackling the problem. Recent research increasingly supports the aim of the Paris Accord at CoP21 to limit temperature increases to less than 2°C, and `to pursue efforts to limit it to 1.5°C'. The Special Report by the Intergovernmental Panel on Climate Change (IPCC) emphasises that the latter is still just achievable, but rapid action is required if it is to be achieved. Among the major likely adverse consequences of ever increasing levels of atmospheric CO2 are extreme weather conditions that can be dangerous to life, including high `wet bulb' heat, wild fires as seen recently in the USA west coast, Amazon, Siberia and Australia, increasingly powerful cyclones, increased coastal flooding as well as inland flooding from `rivers in the sky’, yet more intense and longer droughts. Moreover, there is the potential for climate tipping points, such as when an ice-free Arctic Ocean in the past led to large-scale methane release from permafrost melting in the tundra, causing further rapid climate warming. The added danger of species extinctions, as happened in earlier climate changes, doubly threatens food security, and hence increased flows of refugees and migrants. More positively, sensitive intervention points (SIPs) in the post-carbon transition could induce leverage in both policy actions and technology developments,[1] which will be our focus on here.