Which greenhouse gas should be cut first? Methane, ozone,black carbon (soot) and hydrofluorocarbons have an even morepowerful warming effect, per tonne, than CO2. But a new policypaper by Myles Allen, says that reducing such pollutants while CO2emissions are still rising could make it more difficult to hit the2C goal. He argues that, while there are good reasons to cut them,they should not be used as an excuse to put off cutting CO2emissions.

Carbon Brief speaks to Thomas Stocker, who served asCo-Chair of working group one for the IPCC’s fifth assessmentreport, and who is running to succeed Dr Rajendra Pachauri as IPCCchair. In the interview he discusses his vision for the panel’sfuture, the big climate questions left to answer, attention on the’hiatus’ in AR5, and climate targets: “It will only be a few years[before] the 2C target will become as ambitious as what we are nowdiscussing for 1.5C.”

President Barack Obama took to Twitter on Thursday to answerclimate change-related questions. Obama linked environmentalconcerns to national security and also insisted that ‘the highestpossible standards’ had been set for Shell’s oil drilling inArctic. He took up the question of climate change as a moral issue,aligning himself with Pope Francis, or @Pontifex, and otherreligious leaders. He also linked hurricanes and other extremeweather to climate change, the Washington Timesreports. TheQ&A is the latest move by the President to keep climate changeat the forefront of US politics.

To help green projects at risk of closure, the World Bankhas guaranteed a minimum price for methane credits being auctionedfor the first time. It is hoped it will stimulate investment inprojects ranging from biomass to waste management in developingcountries, curbing emissions of the heat-trapping gas. It says itsplans could reduce 850 million metric tons of carbon dioxideequivalent up to 2020 – the same as taking a billion cars off theroad. On a similar theme, the World Bank also yesterday set a dateand start price for a $25 million UN CO2 credit auction, beginningon July 15, Reutersreports.

Ségolène Royal, France’s environment minister, hascriticised the sluggish pace of UN climate negotiations, sayingthey are so unwieldy they threaten efforts to seal a global warmingdeal in Paris this year, writes the Financial Times. “The procedureisn’t really suited to what we need for climate change,” she saidyesterday, saying negotiators had made little progress on the maintext of the Paris agreement. Elsewhere, Royal told the Guardianthat developingcoutnries are ‘waiting to see’ what rich nations will offer them:”Developing countries are not hostile [to an agreement]; I wouldsay that they are positive, but they are waiting to see. We have tomeet their expectations.” Negotiators from almost 200 countrieshave been working on the draft text since a meeting in Peru lastDecember, and on Monday will gather in Bonn to begin anothertwo-week conference.

The effects of El Nino aren’t confined to the atmosphere: Anew study has found that the cyclical climate phenomenon canratchet up sea levels off the West Coast by almost 8 inches overjust a few seasons. The findings have important implications interms of planning for sea level rise, as ever-growing coastalcommunities might have to plan for even higher ocean levels in awarmer future. “This paper is an important reminder that we cannotneglect interannual sea level variability and we need aquantitative understanding of its impact”, says oceanographer JohnChurch.

European countries must not allow industry experts in theirnational delegations to lobby for weaker coal standards, theEuropean commission’s top environment official has said. The movefollows the finding by the Guardian that toxic pollution limitswere watered down in the face of lobbying from big energycompanies. The commission’s director-general for the environmentwrote a letter, seen by the Guardian, instructing that linesdividing national representatives, industry experts and NGOs shouldbe strictly adhered to in the technical working groups thatnegotiate emissions standards.

Oil companies have frozen dozens of projects in Canada’s tarsands, amid falling prices and a rising tide of protest against oneof the world’s most polluting fossil fuels, the Guardian reports.Some 39 projects containing 13bn barrels of oil are currentlydelayed or on hold, according to analysis by Oil ChangeInternational published today. Exploiting the tar sands, one of themost costly and polluting ways to extract oil, has turned Canadainto the world’s third-largest oil producing nation.

Royal Dutch Shell’s £55bn bid for BG Group faces any numberof hurdles, including volatile oil prices and the risk of acounterbid. But the biggest of all may prove to be China’s Ministryof Commerce, the country’s opaque antitrust regulator, writes theFinancial Times. The deal is the biggest in the energy sector formore than a decade and scrutiny of it will take months.

Climate science denialists love to claim action on climatechange will restrict people’s freedoms, when the opposite could betrue, says Graham Readfearn. Words like “freedom” and “liberty”have essentially been co-opted by those opposed to cuttinggreenhouse gas emissions, becoming a reflex response for too many”free market” conservatives as they try and rationalise anythingthat happens in and around the climate change issue, Readfearnargues.

The “great slanging match” which “passes for the climatechange debate” has just got louder and nastier, says Geoffrey Leanin the Telegraph, referring to the art project at Anglia RuskinUniversity that features the names of six climate skeptics. There’shuge scope for discussing the reality of the science and economics,if only we could all get away from the unproductive “slangingmatch”, he says.

A new study suggests Icebergs breaking off the Greenland icesheet during the last ice age had an unexpected effect – theyincreased the production of methane in the tropical wetlands. Thehuge influx of fresh water into the North Atlantic Ocean from theicebergs pushed the tropical rain belt southwards, intensifying itover a smaller area. The increased rainfall over land caused aboost in methane release around the equator, the researchers say.

New research compares the future impact on global vegetationfrom climate change with that by human activity. Under some of theemissions scenarios used by the IPCC, the researchers find thepoleward expansion of vegetation can hep offset the losseselsewhere from agriculture and deforestation. Overall, theresearchers conclude that humans are likely to cause a largerimpact on land cover changes in the shorter term or under loweremissions scenarios, while climate-induced changes are moresignificant in the longer term or under higher emissions.