A rather late answer on this question, but here goes: The idea that "global temperatures cause the increase of CO2." is fairly easily refuted. The usual line of reasoning is that the solubility of CO2 in water decreases as temperature increases, so the rise in global temperature implies that the oceans will have released some of the dissolved CO2 that it contains. The premise is correct, but the conclusion is a non sequitur as it ignores the fact that the solubility of CO2 in water also depends on the difference in the concentrations of CO2 between the surface ocean and the atmosphere. As we have released CO2 from fossil fuels into the atmosphere, the partial pressure of CO2 in the atmosphere has risen, and so the oceans have been taking up more CO2, not less.
How do we know this is true? . The argument is easily refuted by the
observation that the rate at which atmospheric CO2 levels are rising
is less than the rate at which we are releasing CO2 into the
atmosphere from fossil fuel use, which implies that the natural
environment must be a net carbon sink, taking in more carbon each year
than it emits.
More formally, let Ea represent annual carbon emissions from
anthropogenic sources (fossil fuel use and land use change), En
represent the carbon emissions from all natural sources (the oceans,
soil respiration, volcanos etc.) and Un represent the uptake of carbon
by all natural carbon sinks (oceans, photosynthesis, etc.), Ua would
be the uptake of carbon due to anthropogenic activities, but this is
essentially zero, so we can safely exclude it from the analysis. Then
assuming that the carbon cycle obeys the principle of conservation of
mass (any carbon emitted into the atmosphere that is not taken up by
natural sinks remains in the atmosphere), the annual change in
atmospheric CO2 is given by:
C' = Ea + En - Un
This can be rearranged to give an estimate of the difference between
annual emissions from all natural sources and annual natural uptake by
all natural sinks.
En - Un = C' - Ea
We have accurate, reliable data for the growth of atmospheric CO2 and
for anthropogenic emissions (for details, see Cawley, 2011). Both of
these are displayed below, along with an estimate of the net natural
carbon flux En - Un. The fact that the net natural flux is negative
clearly shows that natural uptake has exceeded natural emissions every
year for the last fifty years at least, and hence has been opposing,
rather than causing the observed rise in atmospheric CO2.
Some time back, I wrote a journal paper refuting a related climate myth, which outlines some of the evidence that the rise in atmospheric CO2 is anthropogenic, and is not a natural phenomenon.
Gavin C. Cawley, "On the Atmospheric Residence Time of Anthropogenically Sourced Carbon Dioxide", Energy & Fuels, volume 25, issue 11, pages 5503–5513, 2011.
This answer is adapted from my answer to a similar question on the Skeptics SE.
"The general consensus is that CO2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies)."
There are actually plenty of studies of this, it is just that the issues were largely resolved over fifty years ago. The main mechanism is the temperature dependent solubility of CO2 in the oceans, there is an excellent textbook on this by Zeebe and Wolf-Gladrow. There is also an effect of temperature on the biosphere, which is a bit more difficult to pin down, but see the references in the relevant section of the IPCC report. The research is there, but we have known for a long time that the rise in CO2 is not the result of natural processes, so there will be no papers explicitly making this claim (at least from people who understand the basics) because there has been no new evidence to support it.