Discover and read the best of Twitter Threads about #metr12
Most recents (9)
6+ statements summarizing why the vast majority of climate scientists think human burning of fossil fuels is causing contemporary global warming. (1/10) #SJSU #Metr12 #GlobalWarming
1) Fundamental physics tells us that increasing greenhouse gas concentrations in the atmosphere should warm the surface, all else equal. This is so fundamental that the greenhouse effect was 1st proposed way back in 1824 (by Joseph Fourier). (2/10)
2) Through burning fossil fuels, humans have increased the concentrations of greenhouse gasses in the atmosphere. CO2 concentrations were nearly constant for thousands of years but have increased by almost 50% since the industrial revolution. (3/10)
There are only 3 fundamental ways to change the Earth’s energy budget: 1) Modification of incoming solar radiation, 2) Modification of the fraction of incoming solar radiation reflected back to space, 3) Modification of the Earth’s outgoing longwave radiation #SJSU #GlobalWarming
A Radiative forcing is something that causes the Earth’s radiative energy budget to become temporarily unbalanced and thus it causes a change in global average temperature. #SJSU #METR12 #GlobalWarming
A Radiative Feedback is something that changes in response to an initial radiative forcing, either amplifying the initial change or reducing the initial change. Relevant radiative feedbacks for Earth are the water vapor feedback, the ice-albedo feedback, and the cloud feedback.
All objects with a temperature above absolute zero emit electromagnetic radiation which is characterized by the peak-to-peak length of the electromagnetic waves (their wavelength) #SJSU #METR12 #GlobalWarming
The Stefan-Boltzmann Law tells us that warmer objects emit more electromagnetic radiation than colder objects and thus emit more energy #SJSU #METR12 #GlobalWarming
Wien’s Law tells us that warmer objects emit a higher proportion of their electromagnetic radiation at shorter wavelengths than cold objects #SJSU #METR12 #GlobalWarming
Temperature is a measure of the average kinetic energy of the molecules in a substance which is related to the average speed of the molecules in that substance.
#SJSU #METR12 #Globalwarming
#SJSU #METR12 #Globalwarming
To increase the temperature of something (with a fixed heat capacity and no work being done) you can increase the amount of energy flowing in, while keeping the amount of energy flowing out the same.
#SJSU #METR12 #Globalwarming
#SJSU #METR12 #Globalwarming
To increase the temperature of something (with a fixed heat capacity and no work being done) you can decrease the amount of energy flowing out, while keeping the amount of energy flowing in the same. #SJSU #METR12 #Globalwarming
Humans exhale CO2 but this does not contribute to global warming because that exhaled carbon was recently obtained from the atmosphere via plant photosynthesis and thus exhaling CO2 is just cycling carbon back to where it was recently extracted. #SJSU #METR12 #Globalwarming
Over the long term (millions of years) silicate-to-carbonate conversion draws CO2 out of the atmosphere and sequesters the carbon in the seafloor. This process is too slow to have any appreciable effect on the CO2 produced from fossil fuel burning. #SJSU #METR12 #Globalwarming
The carbon sequestered on the seafloor makes it back to the atmosphere via subduction of the oceanic crust and volcanic eruptions that release CO2. #SJSU #METR12 #Globalwarming
Each Northern Hemisphere spring, photosynthesis begins to outweigh respiration and global atmospheric concentrations of CO2 decrease. In the fall, the reverse occurs and global atmospheric concentrations of CO2 increase. #SJSU #METR12 #Globalwarming
Humans are altering the global carbon cycle by releasing a reservoir of carbon (that was previously sequestered) into the atmosphere-ocean-land system. #SJSU #METR12 #Globalwarming
The carbon that goes into the atmosphere from the burning of fossil fuels represents only a few percent of the total carbon into the atmosphere annually. But it is not compensated for and thus is responsible for all of the long-term atmospheric increase.
The Kaya Identity shows that one way to affect CO2 emissions would be through population-influencing policies #SJSU #METR12 #Globalwarming 
The Kaya Identity shows that one way to reduce CO2 emissions would be through reduced production/consumption of goods and services (i.e., reduced economic activity) #SJSU #METR12 #Globalwarming
The Kaya Identity shows that one way to reduce CO2 emissions would be through increasing the goods and services that can be produced for a given amount of energy (increasing energy efficiency) #SJSU #METR12 #Globalwarming
Fossil fuels are still used to produce around ~80% of all the energy consumed by humans
#SJSU #METR12 #GlobalWarming
#SJSU #METR12 #GlobalWarming
Fossil fuels are not equal in terms of carbon dioxide (CO2) emissions produced per unit of energy, burning coal releases more CO2 than oil which released more CO2 than natural gas. #SJSU #METR12 #GlobalWarming
Fossil fuels are a non-renewable, limited resource but there are more than enough left to radically alter the climate (~+10C) if we were to burn them all. #SJSU #METR12 #GlobalWarming
I'll be tweeting the main points that we discussed in each of the meetings of the global warming class I am teaching at SJSU. Here are today's, where the broad topics were the current Amazon fires and fossil fuels in general.
#SJSU #METR12 #Globalwarming
#SJSU #METR12 #Globalwarming
1) Our oxygen supply is not in jeopardy due to the current Amazon fires and will not be put in jeopardy from any wildfires.
2) Almost all the energy that is available to us on Earth (including even wind energy and the energy that we use to power our bodies) originated from the nuclear reactions inside the Sun.
