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1.8 (1.3 – 2.3) mm per year during the 1961 – 2003 period, higher between 1993
and 2003 with 3.1 (2.4-3.8) mm per year. In addition, there was an increase in
extreme events such as intense rainfall, heat waves, intensity of tropical
cyclones, etc. According to climate prediction models, the best estimation for
warming at the end of the 21st century (2090-2099) was 0.6 to 4.0ºC, depending
on the best or worst scenario and intermediate simulations.
The Fifth Report (IPCC, 2014) reaffirmed previous findings and conclusions,
emphasizing that the warming of the climate system is unequivocal. It reports
that each of the past three decades (1980-2010) has been successively warmer
than any previous decade since 1850. Many of the observed changes are
unprecedented over decades or millennia. Observational records revealed that
GHG concentrations had increased, making the total radiative forcing positive
and leading to additional energy uptake by the climate system. The largest
contribution to this forcing was caused by the increase in atmospheric CO2
concentration since 1750. The report indicates that:
Human influence on the climate system is unequivocal and detectable.
Therefore, the atmosphere and the ocean show evident warming; snow and ice
covers have decreased, and the sea level has risen. The rise in sea level since
the mid-19th century has been more significant than the average rate for the
previous two millennia. The global mean sea level rose by 0.19 [0.17 to 0.21]
m during 1901-2010. The Report projects that the global surface air temperature
will likely exceed 1.5°C by the end of the 21st century, relative to the 1850-
1900 period, for all but the most benign future climate simulation scenarios. The
Arctic sea-ice extent will likely continue to shrink and thin, and the spring snow
cover in the Northern Hemisphere will decline during the 21st century as global