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Intense Mediterranean Sea heatwave raises fears for marine life - July 2025

Warmer water at the seaside might sound nice for your holiday dip, but recent ocean heat in the Mediterranean Sea has been so intense that scientists fear potentially devastating consequences for marine life.

The temperature of the sea surface regularly passed 30C off the coast of Majorca and elsewhere in late June and early July, in places six or seven degrees above usual.

That's probably warmer than your local leisure centre swimming pool.

It has been the western Med's most extreme marine heatwave ever recorded for the time of year, affecting large areas of the sea for weeks on end.

The heat appears to be cooling off, but some species simply struggle to cope with such prolonged and intense warmth, with potential knock-on effects for fish stocks.

To give you some idea of these temperatures, most leisure centre swimming pools are heated to roughly 28C. Competitive swimming pools are slightly cooler at 25-28C, World Aquatics says.

Children's pools are a bit warmer, recommended at 29-31C or 30-32C for babies, according to the Swimming Teachers' Association.

Such balmy temperatures might sound attractive, but they can pose hidden threats. Harmful bacteria and algae can often spread more easily in warmer seawater, which isn't treated with cleaning chemicals like your local pool.

30 % + of Species could go Extinct with 4° of Warming

How many species could go extinct from climate change? It depends on how hot it gets.

 

Two Kea birds, Arthurs Pass South Island New Zealand. The species is listed as threatened in that country and climate change is among the reasons their numbers are in danger.

Two Kea birds, Arthurs Pass South Island New Zealand. The species is listed as threatened in that country and climate change is among the reasons their numbers are in danger.

 

To consider how climate change could cause some extinctions, imagine a tiny mountain bird that eats the berries of a particular mountain tree.

That tree can only grow at a specific elevation around the mountain, where it's evolved over millennia to thrive in that microclimate. As global temperatures rise, both the tree and the bird will be forced to rise too, tracking their microclimate as it moves uphill. But they can only go so far.

What is biodiversity and how are we protecting it?

 

Baby Amur leopard also known as the Manchurian leopard, at the Parc des felins, in Nesles, south-eastern Paris.

Amur leopards are one of the most endangered species in the world


Targets to reverse the decline of biodiversity by 2030 may be missed without urgent action, according to a new report.

This goal was a key part of the UN global summit on biodiversity held in December 2022.

Nearly a third of all monitored species are currently endangered due to human activities.

Biodiversity targets may be slipping out of reach - 2023

White stork

The researchers studied more than 600 species of birds and mammals


Ambitious targets to halt the decline in nature may already be slipping out of reach, a study suggests.

Scientists say the effects of climate change and habitat loss on animal populations have been underestimated.

They say bringing back wildlife may take longer than expected and that unless we act now global biodiversity targets will be out of reach.

In December almost 200 countries agreed to halt the decline in nature by the end of the decade.