Climate and Energy Action Plan (CEAP)

CLIMATE TRENDS & PRO JECTIONS | CITY OF ASHLAND, OREGON | FINAL REPORT | 30 Figure 22. The natural greenhouse effect intensified by human influence (Walsh et al., 2014a) . How do we know the current warming is human -caused? The b asic physics of the atmosphere says that increa sing atmospheric CO 2 concentration s will cause climate warming through the intensified greenhouse effect . The observed pattern of warming through out the atmosphere is consistent with the pattern expected under the intensified greenhouse effect rather than natural changes. Furthermore, patterns of human -induced change have been identified in many other aspects of the climate system, including changes in ocean heat content, precipitation, atmospheric moisture, and Arctic sea ice. In addition, global climate modeling demonstrates that the observed 20th century warming can only be replicated when human influences are added to natural factors (see Figure 23) (Walsh et al., 2014a, 2014b) .