Natural and anthropogenic substances and processes that alter the Earth's energy budget are drivers of climate change. Radiative forcing14 (RF) quantifies the change in energy fluxes caused by changes in these drivers for 2011 relative to 1750, unless otherwise indicated. Positive RF leads to surface warming, negative RF leads to surface cooling. RF is estimated based on in-situ and remote observations, properties of greenhouse gases and aerosols, and calculations using numerical models representing observed processes. Some emitted compounds affect the atmospheric concentration of other substances. The RF can be reported based on the concentration changes of each substance15. Alternatively, the emission-based RF of a compound can be reported, which provides a more direct link to human activities. It includes contributions from all substances affected by that emission. The total anthropogenic RF of the two approaches are identical when considering all drivers. Though both approaches are

Since the AR4, there has been significant progress in resolving the sea level history of the last 7000 years. RSL records indicate that from ~7 to 3 ka, GMSL likely rose 2 to 3 m to near present-day levels (Chapter 5). Based on local sea level records spanning the last 2000 years, there is medium confidence that fluctuations in GMSL during this interval have not exceeded ~ ±0.25 m on time scales of a few hundred years (Section 5.6.3, Figure 13.3a). The most robust signal captured in salt marsh records from both Northern and Southern Hemispheres supports the AR4 conclusion for a transition from relatively low rates of change during the late Holocene (order tenths of mm yr–1) to modern rates (order mm yr–1) (Section 5.6.3, Figure 13.3b). However, there is variability in the magnitude and the timing (1840–1920) of this increase in both paleo and instrumental (tide gauge) records (Section 3.7). By combining paleo sea level records with tide gauge records at the same localities, Gehrels and Woodworth (2013) concluded that sea level began to rise above the late Holocene background rate between 1905 and 1945, consistent with the conclusions by Lambeck et al. (2004)

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