2020-10-27_PERMIT FILE - C1981035 ‎(22)‎

• Permit No: C1981035
• IBM Index Class Name: Permit File
• Doc Date: 10/27/2020
• Section_Exhibit Name: KII Appendix 16 Dunn Ranch LBA Technical Resources Report
• Media Type: D
• Archive: No

human and ecological systems of small islands, low-lying coastal areas, and deltas (medium
confidence).
• Limiting global warming to 1.5°C compared to 2°C is projected to reduce increases in ocean
temperature as well as associated increases in ocean acidity and decreases in ocean oxygen levels
(high confidence), all of which will reduce risks to marine biodiversity,fisheries, and ecosystems,
and their functions and services to humans.
The following summary text provides an overview of the fourth iteration of the NCA report.
The NCA provides region-specific impact assessments for climate change parameters that are anticipated
to occur throughout this century.The global climate continues to change rapidly compared to the pace of
the natural variations in climate that have occurred throughout Earth's history. Trends in globally
averaged temperature, sea level rise, upper-ocean heat content, land-based ice melt,arctic sea ice,depth
of seasonal permafrost thaw, and other climate variables provide consistent evidence of a warming
planet. These observed trends are robust and have been confirmed by multiple independent research
groups around the world (very high confidence). Many lines of evidence demonstrate that it is extremely
likely that human influence has been the dominant cause of the observed warming since the mid-20th
century. Formal detection and attribution studies for the period 1951 to 2010 find that the observed
global mean surface temperature warming lies in the middle of the range of likely human contributions
to warming over that same period. Natural variability, including El Nino events and other recurring
patterns of ocean—atmosphere interactions, impact temperature and precipitation, especially regionally,
over months to years.The global influence of natural variability, however, is limited to a small fraction of
observed climate trends over decades (very high confidence). Studies found no convincing evidence that
natural variability can account for the amount of global warming observed over the industrial era. For the
period extending over the last century,there are no convincing alternative explanations supported by the
extent of the observational evidence. Solar output changes and internal variability can only contribute
marginallyto the observed changes in climate over the last century,but no convincing evidence for natural
cycles in the observational record can explain the observed changes in climate (very high confidence).
The frequency and intensity of extreme heat and heavy precipitation events are increasing in most
continental regions of the world and these trends are consistent with expected physical responses to a
warming climate. Climate model studies are also consistent with these trends, although models tend to
underestimate the observed trends, especially for the increase in extreme precipitation events (very high
confidence for temperature, high confidence for extreme precipitation). The frequency and intensity of
extreme high temperature events are virtually certain to increase in the future as global temperature
increases(high confidence). Extreme precipitation events will very likely continue to increase in frequency
and intensity throughout most of the world (high confidence). Observed and projected trends for some
other types of extreme events, such as floods, droughts, and severe storms, have more variable regional
characteristics.
Temperatures have increased across almost all of the Southwest region from 1901 to 2016, with the
greatest increases in southern California and western Colorado. The integrity of Southwest forests and
Dunn Ranch Area LBA and Mining Plan Modification 48
Technical Resources Report