Court says rich countries must cut emissions faster than developing nations, and other nature and climate stories you need to read this week

In a landmark ruling for climate justice, the International Tribunal for the Law of the Sea said that states have a legal responsibility to cut the amount of greenhouse gases they produce, to protect the marine environment.

These statements were part of an advisory opinion on climate change issued by the tribunal, which is responsible for interpreting and upholding the 1982 UN Convention on the Law of the Sea, an international treaty representing 169 countries.

The Commission of Small Island States on Climate Change and International Law, a group of nine Caribbean and Pacific island nations led by Antigua and Barbuda and Tuvalu, had requested the advisory opinion – and this is the first time such a document has been issued by an international court.

Speaking to The Guardian, Joie Chowdhury, a senior attorney at the Center for International Environmental Law, said: “It’s the first time an international court has unequivocally affirmed that states do not have unfettered discretion, but specific obligations under international law to act urgently, ambitiously and equitably, to protect oceans from the drivers and impacts of climate change.”

Migrating freshwater fish populations declined by over four-fifths from 1970 to 2020, a study has revealed.

The report by Living Planet Index, published ahead of World Fish Migration Day on May 25, focused on data for fish that move from one habitat to another in a seasonal or cyclical pattern.

On average, the index of 1,864 monitored populations of 284 migratory freshwater fish species from around the world declined 81% from 1970 to 2020 – an average 3.3% drop per year.

The decline was an average of 91% over the 50 years in Latin America and the Caribbean, and about 75% in Europe.

The report was a collaboration among the World Fish Migration Foundation, the Zoological Society of London, the International Union for Conservation of Nature, The Nature Conservancy, Wetlands International and the World Wildlife Fund.

Herman Wanningen, founder of the World Fish Migration Foundation, said:

“The catastrophic decline in migratory fish populations is a deafening wake-up call for the world. We must act now to save these keystone species and their rivers.”

More than half of the world’s mangroves are at risk of collapse, according to the first global assessment for the International Union for Conservation of Nature Red List of Ecosystems. The threat is a result of human activity, rising sea levels and extreme weather and, unless action is taken, a quarter of the world's mangrove areas could be completely submerged within 50 years.

A sixth of the world’s food supplies are threatened by the deterioration of natural pasture land, according to the United Nations Convention to Combat Desertification. Half the world's rangelands have been degraded by climate change and overexploitation, the UN body said.

Cement from demolished concrete buildings can be sustainably recycled, according to scientists from Cambridge University. The world's most common construction material is a huge source of emissions, but the team of scientists says it has found a way to decarbonize the recycling process.

More than 60% of the world's coral reefs have been bleached due to heat stress in the past year, says the leading monitoring agency. The US National Oceanic and Atmospheric Administration says 60.5% of the planet’s reef areas have been affected by the fourth mass bleaching event, as ocean temperatures reach record highs.

As a first-generation observation satellite returns to Earth, we look at six ways satellites are helping to monitor our changing planet from space.

What does it take to thrive as a Chief Sustainability Officer (CSO)? A decade ago, the CSO role did not exist in many organizations, but now it’s a crucial position as businesses around the world try to reduce their environmental impact. We look at the four key attributes a CSO needs to succeed.

Demand for critical minerals has doubled in the past five years, as they play a vital role in the construction of green technologies such as wind turbines, electric vehicles and solar panels. Here are some solutions to boost the critical minerals supply chain.