coastal communities globally and could mean low-lying
islands, such as the Maldives, are lost to the sea.
Melting ice and glaciers also transfer fresh water into the
oceans, which changes the salinity (how much salt is in the
water) of seawater. Over the last 50-odd years, changes in
ocean salinity linked to climate change have corresponded
with shifts in rainfall patterns and an acceleration in the
evaporation and rainfall cycle. Changes in where and how
often it rains has profound repercussions for crop production
and food security.
Variations in rainfall patterns and freshwater input,
along with elevated temperatures, also threaten to disrupt
ocean currents. The oceans are in constant movement,
resulting from surface wind-driven currents and deep-water
thermohaline currents (thermo meaning temperature; haline
meaning salinity). Colder and more saline seawater sinks and
is replaced by warmer surface waters – creating the Great
Ocean Conveyor Belt. Disruption to the oceans’ currents has
the potential to alter global weather patterns, as well as the
migration and dispersal of marine organisms. Already, changes
in thermal stratification (heat layering in the ocean) have
been detected, resulting in reduced mixing of seawater in the
deep ocean. Changes in seawater mixing can decrease nutrient
availability, limiting the fundamental building blocks needed
by marine organisms to grow and sustain life.right bottom One of
Earth’s most vulnerable
nations to climate change,
the Maldive Islands are
severely threatened by rising
sea levelstop The lifestyle of people
living in flood zones in
Indonesia
above right Melting water
gushes from ice in North East
Land, Svalbard in Norway. In
both the Arctic and Antarctic
regions, ice is retreatingabove A waterspout formed
during a large storm off the
coast of the Cayman Islands
IMAGE © EMMA CAMPIMAGE © EMMA CAMP