I'm about to become an Exxon Mobil shareholder...

... and that's a good thing.  I think.

Yesterday's big energy news was Exxon Mobil's $31 billion acquisition of natural gas producer XTO Energy.  In the New York Times:

In the biggest energy deal in years, Exxon Mobil said Monday that it agreed to buy XTO Energy, a domestic producer of natural gas, in an all-stock deal valued at $31 billion to increase its holdings in unconventional resources in the United States.

The deal includes the assumption of $10 billion in debt.

The purchase allows Exxon, the world’s largest publicly traded oil company, to expand in shale gas, an area that has seen tremendous growth in the last few years. It will give Exxon the equivalent of about 45 trillion cubic feet of natural gas throughout the United States.

“XTO is a leading U.S. unconventional natural gas producer, with an outstanding resource base, strong technical expertise and highly skilled employees,” Rex W. Tillerson, Exxon’s chief executive, said in a statement.

“XTO’s strengths, together with Exxon Mobil’s advanced R.&D. and operational capabilities, global scale and financial capacity, should enable development of additional supplies of unconventional oil and gas resources, benefiting consumers both here in the United States and around the world.”

In recent years, energy companies have discovered large reserves of natural gas tightly trapped in shale rocks in Texas, Colorado, and Wisconsin, as well as in the Northeast. The discoveries have led to a gas drilling boom that has greatly expanded domestic resources, while also raising some environmental concerns.

As a *small* shareholder in XTO, I'll get about 0.7 shares of Exxon Mobil (XOM) for every share of XTO when the deal closes in Q2 of next year.  But as someone who cares deeply about climate change, how should I feel about having a financial stake in the success of a company so reviled by environmentalists?

On the one hand, Exxon spearheaded much of the faux science that is behind many of the climate denial myths that persist to this day.  Simply put, without Exxon's efforts in the 90s to cast doubt on climate science, we would probably already have passed climate legislation.

On the other hand, my stock in XTO jumped 15% yesterday, and the bullish news for natural gas boosted my stock in Chesapeake Energy (CHK) by 6% .  And hey, Exxon's going to go about its business regardless of whether I take a stand by not purchasing shares in it, so might as well profit from Exxon's success, right?  At the very least, now no one can say that financial concerns are driving my beliefs about climate change (although full disclosure, the other 90% of my stocks are related to clean energy).

And actually, I have less cynical reasons for being enthused by Exxon Mobil's $31 billion bet on American shale gas.  Because ultimately, I think it signals that Exxon Mobil is finally getting on board with America's clean energy future.

The important point is that generating electricity from natural gas emits half the CO2 as burning coal. Putting a price on carbon (through cap-and-trade) would make it comparatively more expensive for utilities to continue burning coal, and many would switch to natural gas.  Demand for gas would surge, lifting currently-depressed gas prices - as well as profits for gas producers.

I'd originally bought Chesapeake and XTO earlier this year after reading a series of ClimateProgress articles arguing that shale gas would prove a "game changer" in the climate debate, bridging America's dirty energy present with its clean energy future - at a cost much lower than current economic models predict. Now Exxon Mobil agrees with me. 

How does this affect cap-and-trade's chances of passage?  All you have to do is check out where these unconventional shale gas reserves are located:

Most of that pink and purple is over Pennsylvania, West Virginia, and Ohio - big coal states with key swing votes on the climate and clean energy bill.  The prospect for natural gas development in their states should dampen these Senators' concerns about hurting the coal industry.  Same goes for Arkansas and Louisiana, where there are also big shale gas plays.  Exxon clearly believes there's a future for these huge gas reserves.

And this isn't the first investment in clean energy Exxon has made - back in July, the company announced a plan to invest $600 million in a venture to produce fuel from bio-engineered algae.

This of course doesn't make up for Exxon Mobil's past misdeeds.  While I'm holding on to my XOM stock, I won't start buying gasoline at Exxon Mobil gas stations any time soon.  Still, any investment in cleaner technologies is welcome.

Random note to close out the post: many Wall Street analysts seem to think Exxon overpaid for XTO - mainly because natural gas prices are still abysmal.  Last time I checked, buying low was a good thing.  Yet more evidence that few people on Wall Street understand business beyond the next quarter's earnings report.

Bottom line: if you think cap-and-trade will pass, time to start stocking up on gas stocks.