Back in June 1980 Dallas hit a record 113 degrees TWICE two days in a row !!

It hasnt been that hot since.


Natural Climate Factors

" As mentioned, the Earth receives energy from the Sun, loses that energy to space, and is further warmed by the role of greenhouse gases in delaying that energy loss. But there are other natural processes that influence Earth’s surface temperature by changing one of these three parameters. One dramatic process is variations in Earth’s orbit about the Sun that produces significant variations in solar radiation received over time periods measured in several thousand years. Such orbital-caused effects were instrumental in producing past ice ages. Volcanoes emit some CO2, but perhaps sulfate aerosols they emit are more important to short term temperature changes. These aerosols (also produced by some human activity) reflect solar radiation and produce cooling, although the amount is still uncertain. Significant correlation seems to exist between temperature over the past few centuries and solar activity as measured by sunspot numbers. Short-term variations (e.g. decades) in solar output of visible radiation (where the Sun emits most of its energy) is modest and not the sole cause of observed global warming over the past century. However, solar output at other energies is much more variable, and some have argued these contribute to global temperature change. [The two most discussed solar variations are in the ratio of high-energy (UV) to visible radiation, which can change upper atmosphere albedo, and in energetic particle outflow, whose effect on cosmic ray flux is known to change particle ionization in Earth’s atmosphere and possibly alter reflective (higher albedo) cloud cover. Although strong circumstantial evidence exists for both processes, quantitative evidence for their influence on global temperature is lacking.] Another factor producing short term temperature changes, which only recently has been appreciated, is ocean mixing. Because the oceans contain most of Earth’s near-surface heat and because their temperature varies significantly with depth, changes in vertical ocean mixing can and does change surface temperature sufficiently that atmospheric temperature is affected. [The majority of solar radiation directly enters the oceans. The oceans readily influence atmospheric temperatures (e.g. via water evaporation), but transferring atmospheric heat into the oceans is more difficult.] Examples of the effect of oceans were demonstrated by El Nino events in 1997-98 and 2015-16, when warm water upwelling in the tropical Pacific significantly warmed global temperature, which later returned to near previous values. It is known that Ocean currents also have longer term mixing cycles (e.g. the AMO, Atlantic Multidecadal Oscillation, of about 60 years), which are poorly understood. The influence of these cycles on decadal global temperature variations may have been underestimated. Whatever the cause, global temperature over the past few thousand years has varied by up to a few deg-C. One of the larger temperature changes was from the Medieval Period temperature high about 800-1000 years ago (when the Vikings settled Greenland), followed by a drop into the Little Ice Age a few hundred years ago (when western Europe and other regions experienced dramatically colder weather). For the past ~300 years global temperature has been increasing. Prior to the mid-20th century, these global temperature variations could not have been caused by CO2, which remained relatively constant. The Little Ice Age cooling does correspond to a lengthy period of very low solar activity, which has subsequently been increasing. This is suggestive, but does not prove, that solar output played a role in producing these temperature variations. The point is that there have been temperature variations over the past few millennia whose specific cause is not clear (but not due to changing CO2) and that these natural factors may still be occurring and may be unrecognized."