Coral reefs face fourth mass bleaching event, says NOAA, and other nature and climate stories you need to read this week

The world's coral reefs face a fourth mass bleaching event due to record-breaking ocean temperatures driven by the climate crisis and El Nino, according to the National Ocean and Atmospheric Administration (NOAA).

This year is on course to exceed the last mass coral bleaching even between 2014 and 2017, which is thought to have led to around 15% of the planet's reefs experiencing large coral die-offs.

Bleaching turns corals white as the colourful algae that live in them are expelled. Corals can survive a bleaching event but it can stunt growth and affect reproduction.

"It's looking like the entirety of the Southern Hemisphere is probably going to bleach this year," Derek Manzello, coordinator of NOAA's Coral Reef Watch told Reuters.

"We are literally sitting on the cusp of the worst bleaching event in the history of the planet," he said.

A major coral bleaching event is unfolding at Australia's Great Barrier Reef, which is consistent with patterns of heat stress that have built up during the summer months, a government agency has announced.

Climate change could lead to ice-free summers in the Arctic within a decade, researchers say.

The study, published in the Nature Reviews Earth & Environment journal, predicts the region's first ice-free summer day will arrive between 2035 and 2067 - more than 10 years earlier than previous estimates – depending on the impact of global efforts to combat fossil fuel emissions.

In the context of research, ice-free means sea ice cover of an area less than 1 million km squared, effectively leaving the region consisting of mostly water.

Warming atmospheric and ocean temperatures have put average Arctic sea ice levels on a downward trajectory resulting in a decline of 2.7% per decade, data from the National Snow & Ice Data Center shows.

Sea ice forms the habitat of polar bears, seals and numerous other species, and reduces the effect of ocean wave erosion on coastal areas.

Fossilized remains of the world's oldest-known forest have been discovered in sandstone cliffs on the coast of South West England. The find indicates that early trees resembled modern-day palms, with the tallest reaching up to four metres tall, researchers from Cambridge and Cardiff Universities say.

Mass die-offs of farmed salmon are occurring more often and at a bigger scale than ever, with salmon numbers falling by hundreds of millions, according to a study published in the journal Nature.

Months of record rainfall in California has reformed Lake Manly in Death Valley, which dried up thousands of years ago. However, the reappearance may be short-lived as water levels are already receding.

The European Union's Copernicus Climate Change Services has confirmed that 2024 was the warmest February ever recorded, with global sea surface temperatures reaching record highs.

Women in rural communities are harder hit economically than men by the climate crisis and the gap is likely to increase, according to new research by the United Nations' Food and Agriculture Organization.

Greece has experienced its hottest-ever winter, raising concerns of a repeat of the summer wildfires that ravaged parts of the country in recent years. Average peak winter temperatures were 11.3°C higher than the average top winter levels between 1960 and 2024, the National Observatory of Athens says.

The sinking of the Rubymar bulk carrier by Houthi rebels risks leaking fuel and spilling thousands of tonnes of fertilizer into the Red Sea, posing a serious threat to the environment, experts have warned.

Bio-based urban construction can help build a greener future by shifting from concrete and steel structures to lower-carbon building materials, such as timber and bamboo. Here's how.

The most appropriate climate policy is a matter of opinion. A global survey reveals what scientists think about different climate policy approaches and why this matters.

How can financiers like banks, insurance companies and investors help accelerate the transition to a nature-positive economy? A raft of new agreements from business leaders provide some options.