The first significant step to putting the Paris Climate Agreement into practice will take place at the UN headquarters in New York today. Around 155 countries are expected to formally sign the deal at the UN, including around 60 world leaders such as French President Francois Hollande and Prime Minister Trudeau from Canada. But their signatures alone will not be enough to make the agreement operational – each country will also have to go through a process of ratification. However, some environmentalists have dismissed the event as a “distraction”, and experts say the plans are not ambitious enough, reports the New York Times. “For all the signs of progress and political will, however, new challenges to implementing the accord have arisen just since December”, the New York Times writes. Elsewhere, the Financial Times highlights that “much has changed since nearly 200 countries struck the deal in December”, from new temperature records, to the bankruptcy of Peabody Coal, to the ascendancy of Republican contender Donald Trump. Carbon Brief has an explainer detailing the distinctions between adopting, signing and ratifying the UN climate deal. Climate Home also covers the story.

The difference between 1.5C and 2C of warming finds extra 0.5C would mean longer heatwaves, greater droughts and threats to crops, according to the first comprehensive analysis of the issue. Coral reefs, which provide vital nurseries for many fish on which people rely on for food, would be particularly affected by an additional 0.5C of warming. “In a [2C] scenario, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards” the scientists found. The Paris climate deal agreed in December pledged to “hold the increase in the global average temperature to well below 2C above pre-industrial levels and pursue efforts to limit the temperature increase to 1.5C.” Carbon Brief and New Scientist also cover the new research.

Plans to build an £18 billion nuclear power plant at Hinkley Point, were denounced by Jean-Vincent Placé, France’s minister for reforming the state. “EDF absolutely must rethink its strategic vision,” Mr Placé said, calling the plans financially unstable and precarious. The comments reflect a deepening rift in President Hollande’s cabinet over the scheme, the Times reports. Elsewhere, the Financial Times reports that any French government financial support to EDF to enable the company to build the Hinkley Point C nuclear power station in the UK would “almost certainly be blocked” by the European Commission, according to legal opinion commissioned by Greenpeace.

Twenty-four people died after a leak caused a deadly petrochemical plant blast, and the death toll could still rise, Mexican oil giant Pemex said yesterday. The accident is the latest in a series of fatal accidents to hit the company, Reuters reports.

The area of frozen ice in the Arctic could shrink to a record low this year, new research finds. The Arctic Ocean ice cover is already unusually thin after record hot temperatures last summer caused considerable melting – while the unprecedented warm winter weather that followed meant far less of the lost ice was replenished, iNews reports. “The current ice conditions are similar to those of the spring of 2012 – in some places, the ice is even thinner,” Dr Marcel Nicolaus, of Germany’s Alfred Wegener Institute, told the EGU conference. Carbon Brief also covered the findings.

A group of world leaders and international finance chiefs has urged the world to rapidly expand the pricing of carbon pollution, ahead of a UN ceremony where some 155 countries are expected to sign the Paris Climate Agreement. The group includes the Prime Ministers of Canada and Ethiopia, the Presidents of Chile, France and Mexico, the Chancellor of Germany and the head of the IMF and World Bank. They believe that the world can achieve 25% of emissions covered by carbon pricing by 2020 while half the world’s output could be covered by 2025. “There is a growing sense of inevitability about putting a price on carbon pollution,” said World Bank President Jim Yong Kim. “Prices for producing renewable energy are falling fast, and putting a price on carbon has the potential to make them even cheaper than fuels that pollute our planet.” India has also called on rich countries to put a tax on coal to help poorer nations adapt to climate change.

The global coral bleaching event devastating the Great Barrier Reef has spread to reefs in Western Australia, the Guardian reports. Marine protections, which help coral reefs recover from bleaching, were halted in Western Australia when the Coalition was elected. Between 60% and 90% of coral at the renowned and isolated Scott Reef have been bleached in water as deep as 15m, according to the latest reports.

The Paris agreement was a breakthrough, but it is up to all of us to act as guardians of these new standards, say Leonardo DiCaprio, actor and UN Messenger of Peace, and Fred Krupp, president of the Environmental Defense Fund, in the Guardian. “Limiting average temperature increase could be the difference in assuring our future”, they write. In order to deliver on the promise of Paris they argue that our work should follow five basic principles: reducing and pricing carbon emissions, accelerating the transition to renewable energy, protecting the world’s vital ecosystems, taking aggressive short-term action first, and making our cities global models for sustainability.

The government should acknowledge that the decision to build Hinkley Point C is an error before further expense and political stasis makes it unstoppable nuclear power station, argues an editorial in the Times. Reducing carbon emissions “is certainly a good reason for committing to nuclear energy as an integral part of Britain’s energy mix”, but that “does not in itself justify Hinkley Point, for which the criterion should be value for money”.

The signing of the Paris Agreement together with the Tata Steel crisis should provide the UK with the impetus it needs to finally deliver an ambitious low carbon industrial strategy, argues Labour peer Baroness Worthington in BusinessGreen. “With the right policies, we can show that climate action can act as a spur for industrial innovation and investment, securing jobs for the remainder of this century”, she writes.

Very long term climate change is governed more by the waxing and waning of volcanism and less by erosion, according to new research. A study of global sedimentary deposits demonstrate a direct relationship between volcano activity and major climate shifts over 720 million years, matching widespread activity to the early Paleozoic and Mesozoic climates and reduced activity to the icehouse climates of the Cryogenian, Late Ordovician, late Paleozoic and Cenozoic.