Honolulu,
Hawaiʻi, 5 September (IUCN) – Ocean warming is affecting humans in
direct ways and the impacts are already being felt, including effects on
fish stocks and crop yields, more extreme weather events and increased
risk from water-borne diseases, according to what has been called the
most comprehensive review available on the issue, launched today by the
International Union for Conservation of Nature (IUCN) at the IUCN World
Conservation Congress in Hawai‘i.
The report, Explaining ocean warming: Causes, scale, effects and consequences,
reviews the effects of ocean warming on species, ecosystems and on the
benefits oceans provide to humans. Compiled by 80 scientists from 12
countries, it highlights detectable scientific evidence of impacts on
marine life, from microorganisms to mammals, which are likely to
increase significantly even under a low emissions scenario.
“Ocean warming is one of this generation’s greatest hidden challenges – and one for which we are completely unprepared,” says IUCN Director General Inger Andersen.
“The only way to preserve the rich diversity of marine life, and to
safeguard the protection and resources the ocean provides us with, is to
cut greenhouse gas emissions rapidly and substantially.”
Ocean
warming is already affecting ecosystems from polar to tropical regions,
driving entire groups of species such as plankton, jellyfish, turtles
and seabirds up to 10 degrees of latitude towards the poles, causing the
loss of breeding grounds for turtles and seabirds, and affecting the
breeding success of marine mammals, according to the report.
By
damaging fish habitats and causing fish species to move to cooler
waters, warming oceans are affecting fish stocks in some areas and are
expected to lead to reduced catches in tropical regions, the report
states.
In
East Africa and the Western Indian Ocean, for example, ocean warming
has reduced the abundance of some fish species by killing parts of the
coral reefs they depend on, adding to losses caused by overfishing and
destructive fishing techniques. In South-East Asia, harvests from marine
fisheries are expected to fall by between 10% and 30% by 2050 relative
to 1970-2000, as the distributions of fish species shift, under a high
‘business as usual’ greenhouse gas emission scenario, the report states.
“Most
of the heat from human-induced warming since the 1970s – a staggering
93% – has been absorbed by the ocean, which acts as a buffer against
climate change, but this comes at a price. We were astounded by the
scale and extent of ocean warming effects on entire ecosystems made
clear by this report,” says Dan Laffoley, Marine Vice Chair of the World Commission on Protected Areas at IUCN, and one of the lead authors.
The
report also highlights evidence that ocean warming is causing increased
disease in plant and animal populations, and impacting human health as
pathogens spread more easily in warmer waters, including cholera-bearing
bacteria and harmful algal blooms that cause neurological diseases like
ciguatera.
Warming
oceans are also affecting the weather, with a range of knock-on effects
on humans. The number of severe hurricanes has increased at a rate of
around 25-30% per degree of global warming, the report states.
Ocean
warming has led to increased rainfall in mid-latitudes and monsoon
areas, and less rain in various sub-tropical regions. These changes will
have impacts on crop yields in important food-producing regions such as
North America and India, according to the report.
The
protection against climate change offered to us by oceans and their
ecosystems – such as absorbing large amounts of CO2 and sheltering us
from storms and erosion – is also likely to reduce as the ocean warms,
according to the report.
The
report’s recommendations include recognising the severity of ocean
warming impacts on ocean ecosystems and the benefits they provide to
humans, expanding marine protected areas, introducing legal protection
for the high seas, better evaluating the social and economic risks
associated with warming oceans and continuing to fill gaps in scientific
knowledge, as well as cutting greenhouse gas emissions rapidly and
substantially.
Ocean
conservation is one of the major themes addressed by the ongoing IUCN
Congress, where IUCN Members will vote on motions related to protecting the high seas and protected areas in Antarctica among many others.
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