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At the same time, the observation, processing, and data processing capacities
have improved and expanded in the last three decades, allowing the detection
of observed changes with increasing certainty. Satellite climate records and new
improved analyses have been used as an additional line of evidence to assess
changes on a global and regional scale. However, there is still room to increase
the coverage or continuity of some observation data and access to data that are
still protected by internal policies of the countries that can further increase the
certainty
of
the
observed
changes.
The results of the Sixth Report
reaffirm
that
the
observed
changes
in
climate
are
unequivocal at the global scale
and increasingly evident at the
regional and local spatial scales.
Both
the
long-term
rate
of
change
and
the
amplitude
of
year-to-year
variations
differ
between
regions
and
between
climate
variables,
influencing
when changes emerge or become
apparent
compared
to
natural
variations.
The
evidence
for
human
influence
on
recent
climate
change
has
grown
progressively stronger from the Second to the Fifth Reports, and it is even
stronger in the latest assessment, even for regional and extreme scales. Human
influence in the context of the IPCC refers to human activities that lead to or
contribute to a climate response, such as human-induced GHG emissions that
subsequently alter the radiative properties of the atmosphere, resulting in
warming of the components of the atmosphere, ocean, and land. Other human
activities that influence climate include the emission of aerosols and other short-
lived weather agents, and land-use change, such as urbanization. Progress in
understanding human influence is made from longer-term observational data
sets and improved paleoclimate information. Since the Fifth Report, attribution
to human influence has become possible across various climate variables and
climate impact drivers.
In addition to global surface temperature, a wide range of indicators across all
climate system components are changing rapidly, many at levels not seen in