NEW MEXICO

   

Figure 1

Figure 1: Observed and projected changes (compared to the 1901–1960 average) in near-surface air temperature for New Mexico. Observed data are for 1900–2018. Projected changes for 2006–2100 are from global climate models for two possible futures: one in which greenhouse gas emissions continue to increase (higher emissions) and another in which greenhouse gas emissions increase at a slower rate (lower emissions)¹. Temperatures in New Mexico (orange line) have risen about 2°F since the beginning of the 20th century. Shading indicates the range of annual temperatures from the set of models. Observed temperatures are generally within the envelope of model simulations of the historical period (gray shading). Historically unprecedented warming is projected during the 21st century. Less warming is expected under a lower emissions future (the coldest years being about 1°F cooler than the hottest year in the historical record; green shading) and more warming under a higher emissions future (the hottest years being about 10ºF warmer than the hottest year in the historical record; red shading). Source: CICS-NC and NOAA NCEI.<br><br>¹Technical details on models and projections are provided in an appendix, available online at: <a href="https://statesummaries.ncics.org/pdfs/TechInfo.pdf">https://statesummaries.ncics.org/pdfs/TechInfo.pdf</a>.

New Mexico encompasses a large geographic area of diverse interior-continental environments, including mountain ranges, forests, grasslands, and deserts. Temperature varies widely across the state. Monthly average temperatures in the northern mountainous regions range from the low 20s in January to around 60 in July while in the lower elevations in the south the range is from middle 40s in January to low 80s in July. Much of the state is characterized as arid to semi-arid with most areas in the central and west receiving less than 15 inches of precipitation annually.

The last decade has been the warmest on record for the state (Figure 1), with increasing trends in both extremely hot days and warm nights. Over the past several decades, much of the state has seen increases in the number of extremely hot days (maximum temperature at or above 100°F; Figure 2), most prominently in the eastern plains. A similar trend is apparent in the number of warm nights (minimum temperature at or above 70°F; Figure 3), which has increased since the mid-1970s, and in winter temperatures, as the number of very cold nights (minimum temperature at or below 0°F) was below average during the 1990–2009 and 2015–2018 periods (Figure 4a).

Precipitation is highly variable from year to year, and decade to decade. Statewide annual precipitation has ranged from a high of 26.57 inches in 1941 to a low of 6.58 inches in 1956. The wettest multi-year periods were in the early 1940s and mid-1980s (Figure 4b) with the wettest 5-year period being 1984–1988. The driest multi-year periods were in the early 1950s and early 2010s (Figure 4b) with the driest 5-year period being 1952–1956. Multi-year periods of high and low precipitation have resulted in very large swings in reservoir supplies for agriculture. Levels in the Elephant Butte Reservoir were high from the 1920s to the 1940s before dropping to low levels until the 1980s. High levels remained throughout the 1980s and 1990s until falling again in the first part of the 21st century (Figure 5). This illustrates that there have been extended (decades-long) periods of unusual wet or dry conditions. The latest multi-year drought (2011–2014; the second-worst statewide drought since the early 1950s) resulted in near record low levels of water in the reservoir.

Unlike many areas of the United States, New Mexico has not experienced an upward trend in the frequency of extreme precipitation events; although the value for the 2015 to 2018 period was the highest on record, it is too short a period to constitute a trend (Figure 4c). The annual number of extreme precipitation events (days with precipitation of 1 inch or more) has been variable over the past three decades, fluctuating in a similar fashion to the pronounced variations in total annual precipitation (Figure 4b). Since drought conditions began in the 2000s, the occurrence of these events was near or below average until the 2015–2018 period, with a higher than average number of events.

An important feature of New Mexico’s summer climate is the North American Monsoon, which causes July and August to be the wet season across much of the state (Figure 4d). In some regions of the state, monsoon rainfall accounts for half of the annual precipitation and plays an important role in supporting the agricultural economy. The monsoon rains are highly beneficial, but can occasionally be destructive. In 2006, a remarkably persistent monsoon regime was in place from late July through most of August, and caused significant damage and flooding in southern New Mexico. This was seen again in the summer of 2013 when a single, very wet week in September caused major flooding across the central and western portions of the state. These events provided much-needed water for the reservoirs, but also caused widespread damage.

Under a higher emissions pathway, historically unprecedented warming is projected by the end of the 21st century (Figure 1). Even under a pathway of lower greenhouse gas emissions, average annual temperatures are projected to most likely exceed historical record levels by the middle of the 21st century. However, there is a large range of temperature increases under both pathways, and under the lower pathway, a few projections are only slightly warmer than historical records. Heat waves are projected to increase in intensity, posing a risk to human health, while cold wave intensity is projected to decrease.

Although projections of annual precipitation are uncertain, precipitation in spring, already the dry season in New Mexico, is projected to decrease across most of the state> (Figure 6). Decreased precipitation in the spring, combined with warmer temperatures, would have profoundly negative impacts on mountain snowpack that feeds water supply reservoirs, reducing water flow to the river basins, which rely on the snowpack for summer water supplies. Even if snowpack accumulation were not to decrease, the projected higher temperatures will lead to an earlier initiation and earlier end to the snowmelt season, potentially necessitating changes in water management.

The extended record indicates that droughts are a frequent occurrence in New Mexico and episodes more severe than any in the recent historical record have occurred in the more distant past (Figure 7). Droughts are projected to become more intense. Recent drought conditions have negatively impacted ecosystems across the state. For example, extreme drought in the Chihuahuan Desert has caused grasslands to die, decreasing grazing resources for livestock. While projections of changes in precipitation are uncertain, higher temperatures will increase water evaporation from moist and vegetated surfaces. This will reduce streamflow and soil moisture, increasing the intensity of naturally occurring droughts. Drought will not only further challenge limited agricultural resources but also increase the occurrence and severity of wildfires and the frequency of dust storms.

RESOURCES

1. Hayhoe, K., D.J. Wuebbles, D.R. Easterling, D.W. Fahey, S. Doherty, J. Kossin, W. Sweet, R. Vose, and M. Wehner, 2018: Our changing climate. Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 72–144. [URL]
2. Kunkel, K.E., L.E. Stevens, S.E. Stevens, L. Sun, E. Janssen, D. Wuebbles, K.T. Redmond, and J.G. Dobson, 2013: Regional climate trends and scenarios for the U.S. National Climate Assessment. Part 5. Climate of the Southwest U.S. NOAA Technical Report NESDIS 142-5, 83 pp. [URL]
3. MRCC, n.d.: Maps of gridded data—Long-term averages: “1981–2010; Average temperature; New Mexico.” Midwestern Regional Climate Center. Retrieved August 19, 2019. [URL]
4. NOAA, n.d.: Climate at a glance: Statewide time series. National Oceanic and Atmospheric Administration National Centers for Environmental Information. Retrieved August 19, 2019. [URL]
5. NOAA, n.d.: Climate of New Mexico. National Oceanic and Atmospheric Administration National Climatic Data Center. Retrieved August 19, 2019. [URL]
6. NOAA, n.d.: NWS ABQ—2013 September Flooding. National Oceanic and Atmospheric Administration National Weather Service. Retrieved September 9, 2019. [URL]
7. USBR, n.d.: Upper Colorado region: Water operations: Historic Data. United States Bureau of Reclamation. Retrieved September 9, 2019. [URL]
8. Vose, R.S., D.R. Easterling, K.E. Kunkel, A.N. LeGrande, and M.F. Wehner, 2017: Temperature changes in the United States. Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart, and T.K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 267–301. [URL]