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living organisms, as well as diseases that they impart to plants and animals. Changes in
climate will impact each pest differently, including geographic shifts, their survivability
through dormant periods, their growth and impact during other times, and the vulnerability of plants and animals to their effects. Agricultural use of pesticides can limit some
impacts and will likely need to be used in different ways under different climates in
different locations. However, some parasites are not controllable with pesticides.
Overall,
the effects of climate change on crop and terrestrial food production are evident in several
regions of the world (high confidence). Negative impacts of climate trends have been more
common than positive ones. Positive trends are evident in some high latitude regions (high
confidence)… periods of rapid food and cereal price increases following climate extremes
in key producing regions, indicating a sensitivity of current markets to climate extremes,
among other factors.
For the major crops (wheat, rice, and maize) in tropical and temperate regions, climate change
without adaptation will negatively impact production for local temperature increases of 2 °C
or more above late-20th-century levels, although individual locations may benefit (medium
confidence). Projected impacts vary across crops and regions and adaptation scenarios, with
about 10% of projections for the period 2030–2049 showing yield gains of more than 10%
and about 10% of projections showing yield losses of more than 25%, compared to the late
20th century. After 2050, the risk of more severe impacts increases. Regional [studies] …
show crop production to be consistently and negatively affected by climate change in the
future in low-latitude countries, while climate change may have positive or negative effects in
northern latitudes (high confidence). Climate change will increase progressively the interannual variability of crop yields in many regions (medium confidence).
While the preceding has focused on land-based agriculture, climate change is also
significant for food from marine and freshwater fisheries. Warming of oceans results
is a reduction of fish catches in lower (warmer) latitudes, and likely expansion of fish
catches in higher (colder) latitudes. Ocean acidification caused by the absorption of
excess CO 2 in the atmosphere is also impacting fisheries. Of course, such changes are
occurring against an ongoing trend in unsustainable fishing at all latitudes.
One aspect of food production frequently overlooked is the nutritional content of
food, which is also impacted by climatic conditions. Such impacts are like other
climate impacts, specific to the crop and the attribute (temperature extremes, CO 2
concentration, etc.)
Finally, the likelihood of more intense and frequent weather events (storms,
floods, droughts, etc.) means that, in the absence of other changes to agriculture, it
is likely that there will be greater variability in food production as the climate warms
threatening the stability of food supplies.
11.4.2.2 Climate Change Impacts on Land for Water
Land can be set aside or managed for ecosystem functions such as for water capture
and storage based upon existing local precipitation patterns and ecosystem services.
Changes in precipitation will necessitate changes in land requirements for water,
which may include new lands utilized for water capture and storage diverted from
agricultural use.
11 Climate Change
living organisms, as well as diseases that they impart to plants and animals. Changes in
climate will impact each pest differently, including geographic shifts, their survivability
through dormant periods, their growth and impact during other times, and the vulnerability of plants and animals to their effects. Agricultural use of pesticides can limit some
impacts and will likely need to be used in different ways under different climates in
different locations. However, some parasites are not controllable with pesticides.
Overall,
the effects of climate change on crop and terrestrial food production are evident in several
regions of the world (high confidence). Negative impacts of climate trends have been more
common than positive ones. Positive trends are evident in some high latitude regions (high
confidence)… periods of rapid food and cereal price increases following climate extremes
in key producing regions, indicating a sensitivity of current markets to climate extremes,
among other factors.
For the major crops (wheat, rice, and maize) in tropical and temperate regions, climate change
without adaptation will negatively impact production for local temperature increases of 2 °C
or more above late-20th-century levels, although individual locations may benefit (medium
confidence). Projected impacts vary across crops and regions and adaptation scenarios, with
about 10% of projections for the period 2030–2049 showing yield gains of more than 10%
and about 10% of projections showing yield losses of more than 25%, compared to the late
20th century. After 2050, the risk of more severe impacts increases. Regional [studies] …
show crop production to be consistently and negatively affected by climate change in the
future in low-latitude countries, while climate change may have positive or negative effects in
northern latitudes (high confidence). Climate change will increase progressively the interannual variability of crop yields in many regions (medium confidence).
While the preceding has focused on land-based agriculture, climate change is also
significant for food from marine and freshwater fisheries. Warming of oceans results
is a reduction of fish catches in lower (warmer) latitudes, and likely expansion of fish
catches in higher (colder) latitudes. Ocean acidification caused by the absorption of
excess CO 2 in the atmosphere is also impacting fisheries. Of course, such changes are
occurring against an ongoing trend in unsustainable fishing at all latitudes.
One aspect of food production frequently overlooked is the nutritional content of
food, which is also impacted by climatic conditions. Such impacts are like other
climate impacts, specific to the crop and the attribute (temperature extremes, CO 2
concentration, etc.)
Finally, the likelihood of more intense and frequent weather events (storms,
floods, droughts, etc.) means that, in the absence of other changes to agriculture, it
is likely that there will be greater variability in food production as the climate warms
threatening the stability of food supplies.
11.4.2.2 Climate Change Impacts on Land for Water
Land can be set aside or managed for ecosystem functions such as for water capture
and storage based upon existing local precipitation patterns and ecosystem services.
Changes in precipitation will necessitate changes in land requirements for water,
which may include new lands utilized for water capture and storage diverted from
agricultural use.
11 Climate Change