Top scientists will launch a study this week on how and whether a 1.5C global warming limit could be met, Reuters reports. It adds: “many of them fear it might be too late to reach that level”. According to the article, UN climate chief Christiana Figueres told a London conference yesterday: “Do we know how [to reach 1.5C]? No. It is definitely a moon shot”. The Washington Postpreviews the 22 April signing ceremony for the Paris climate agreement, noting: “it is far from clear…[if we] know how to limit warming to 2 or 1.5C”.

Greenhouse gas emissions were responsible for two-thirds of sea level rise between 1970 and 2005, reports Climate Central, covering new research published in Nature Climate Change. Natural forces caused two-thirds of rises detected between 1900 and 1950, it says. The authors of the research discuss their work in an article for the Conversation.

Dozens of investors are backing a call for ExxonMobil to “stress test” the impact of climate policies on its business, reports the Financial Times. Shareholder proposals have been submitted to the annual meetings of Exxon and eight other US energy firms, it says. Those leading the Exxon proposal include the New York state retirement fund and the Church of England. Separately, Rachel Kyte, chief of the UN’s Sustainable Energy for All initiative has warned investors to consider how a 1.5C warming limit would affect their portfolios, reports Climate Home.

The global steel crisis is also affecting firms in the US, reports the Financial Times. US Steel lost $1.5bn last year, it reports, as the industry there grapples with “the same surge of cheap Chinese exports that has devastated the sector’s economics worldwide”. Meanwhile in the UK, Tata Steel has agreed the sale of its Scunthorpe plant and is in talks with the government over a potential co-investment with the private sector, reports the BBC. Carbon Brief has also looked at the UK steel crisis.

UN climate chief Christiana Figueres has predicted that the Paris climate treaty will come in to effect by 2018, Bloomberg reports. She also said the deal had come “10 years too late”. TheWashington Post looks at how president Obama’s intention to ratify the Paris agreement before leaving office could bind the next president to the deal, even if that president is opposed to acting on climate change.

The Climate Ready advice service that was set up to help businesses cope with flooding and climate change has been shut down, reports the Times, citing a leaked Environment Agency email. The service “helped dozens of small businesses in Lancashire and Cumbria devastated by floods in December”, the paper notes. Climate Local, which helped councils tackle similar issues, has also been closed.

A special report on 1.5C from the Intergovernmental Panel on Climate Change (IPCC) should focus on scientific and political uncertainties, not on developing “unachievable mitigation pathways”, writes Glen Peters in Nature Climate Change. “Very few 2C scenarios assume plausible political narratives”, he writes, for instance assuming globally uniform carbon prices from 2010. Rather than simply focus on scenario development, the IPCC 1.5C report should look at issues like political feasibility and social acceptability. Peters also questions the utility of the “remaining carbon quota” concept and points to other key knowledge gaps the IPCC should address.

Five years on from Fukushima and 30 years after Chernobyl “widespread confusion…still blights rational discussion on energy”, argues David Robert Grimes in the Guardian. The health impact of Chernobyl is “far less than people tend to believe”, he writes, a reality that is “largely ignored” by “ideological opponents of nuclear power”. Nuclear energy has drawbacks but it “must be considered if we are to halt climate change”, he concludes.

Ahead of the Intergovernmental Panel on Climate Change (IPCC) meeting in Nairobi later this week, serial IPCC lead author Richard Klein reflects on the work facing the institution. It has been invited to produce a special report on a 1.5C warming limit but must also consider 27 other proposals for reports on topics from cities to carbon markets.

Fossil fuel and industrial CO2 emissions need to peak 5–10 years earlier than expected and the carbon budget for 2C needs to be reduced by 6–17% to offset the extra warming that is likely to come from thawing permafrost, according to new research. The pool of carbon buried in Arctic and sub-Arctic permafrost that is susceptible to thaw is higher than previously thought and even a low emissions pathway is likely to see some of it released by 2100, the authors warn.

The influence of greenhouse gases and aerosols accounts for 15% of observed sea level rise before 1950 but becomes the dominant contributor after 1970, accounting for 72% of sea level rise in 2000. The study, which aims to attribute global sea level rise from thermal expansion and ice melt to its constituent drivers, finds an essentially zero contribution from natural radiative forcing over the 20th century.

A new study projects that by mid century, 73% of island groups – home to 16 million people – will become drier as climate change disrupts the terrestrial water balance. Extra stress on freshwater sources will likely have important consequences for already vulnerable human populations living on islands across the world, about which few projections have been made because they are typically too small for conventional climate models to “see”.