Climate change: another threat to cetaceans 
Nowadays we all have probably heard about climate change. Increases in temperature, strong rainfall, droughts, increased storm intensity, etc. But, what changes occur in the sea? How do they affect the beings that inhabit the sea, including marine mammals?
One of the main causes of climate change is the emission of greenhouse gases into the atmosphere, among which there is carbon dioxide (CO2). These gases absorb the light radiation reflected or emitted by the sea and Earth's surface, preventing its release into the space. The retained heat causes an increase in global surface and ocean temperature, which, in turn, leads to sea ice melting, rise in sea levels, among other effects.
In the oceans there is a balance between carbon compounds, including CO2, bicarbonate and carbonate ions. Due to increased atmospheric CO2, the absorption rate of this gas in the oceans has increased, causing acidification of the sea and alterations in the carbon compounds balance. This mainly affects small organisms with calcareous exoskeletons that require high concentrations of calcium carbonate, among which we find the reef-building corals, one of the marine ecosystems that support the high levels of biodiversity.
It is difficult to predict the consequences of these changes on the oceanic environment and communities, however it is expected that changes in ecosystems as productive as are coral reefs and the Antarctic, lead to an alteration in the species composition of these communities, affecting prey availability (fish, squid, zooplankton) for marine mammals. In turn, as oceanographic conditions (temperature, pH, salinity, productivity) change, the home ranges and migratory circuits of many species may vary as well. The distributions of cetaceans are closely related to sea temperatures, so an increase in sea temperature could lead to a movement of these species to higher latitudes. If this displacement happens the species living currently in these latitudes would be affected by an increase in competition for food and habitat.
It is thought that the species in most immediate risk are those whose home ranges are restricted, in particular species for which the polar regions are key habitats due to the increasing loss of polar ice.
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