我是 LaTeX 的新手，并且渴望学习，因为我正在攻读博士学位，并且有人告诉我 LaTeX 是编写科学文献的绝佳平台。
因此，我在 TeXstudio 中写了一篇简短的纯英文文章，但遇到了一些问题：
\documentclass[a4paper,10pt]{article}
\usepackage{natbib}
\usepackage{graphicx}
\usepackage{gensymb}
\usepackage{url}
\usepackage{wrapfig}
\bibliographystyle{plainnat}
\begin{document}
\begin{figure}[h!]
\centering
\includegraphics[width=1\textwidth]{withstupid}
\caption{I'm with stupid \citep{adcock2018}}
\end{figure}
{\LARGE Save our planet and our species, now!?} \\
The human species faces the most important crossroads in our history, we have two choices; [1] to continue down our existing path, ignoring the impact our actions are having on the environment or [2] to take immediate action and reduce our carbon dioxide emissions, in an attempt to manage the rate of global warming and save not just the very planet we depend on to survive but also to secure a future for our own species. I believe our species is currently facing an existential risk of our own making. \\
Analysis of air bubbles from ice in the poles has shown that for thousands of years, the $CO_2$ levels in the atmosphere was stable at around 280 PPM, until 1800, when the $CO_2$ concentrations begin to exponentially increase. The start of the industrial revolution circa 1900 marked an unprecedented rate of increase in measured $CO_2$ levels in the atmosphere.\\
We burn fossil fuels to generate electricity, fuel vehicles and power industry. When we burn fossil fuel or biomaterial it produces $CO_2$ among other things. Laboratory analysis allows us to trace the sources of $CO_2$ in the atmosphere and there is no doubt that the increase in $CO_2$ is a result of human activity.\\
Fast forward to 2018 and the current levels of carbon dioxide in the atmosphere are 408PPM and rising every day. These are the highest levels measured in over 800,000 possibly even the last 20 million years.\\
\begin{figure}[h!]
\centering
\includegraphics[width=0.5\textwidth]{co2variation}
\caption{$CO_2$ variation \citep{Wikipedia17122018}}
\end{figure}
$CO_2$ is a greenhouse gas and excess levels of this gas in the atmosphere are increasing the greenhouse effect, trapping more heat in the atmosphere and raising the temperature of the Earth. Increasing global temperatures will cause irreversible damage to the environment and ecosystems around the planet.\\
International recognition of this risk resulted in a landmark agreement between Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris on 12th December 2015. It was agreed to combat climate change by maintaining a global temperature rise below 2\degree C above pre-industrial levels and to pursue actions to further limit the global temperature rise to 1.5\degree C. To date: 195 Parties have signed the Agreement, 179 Parties ratified. The Parties include industrialized (developed) countries and developing countries alike. \\
\begin{figure}[h!]
\centering
\includegraphics[width=0.5\textwidth]{parties}
\caption{Countries signed Paris agreement \citep{ratified}}
\end{figure}
To date temperatures have increased by around 1\degree C and we have witnessed significant climate events around the planet – extreme weather events, flooding, fires, coral bleaching, drought and heat waves.
On the 8th October 2018, the Intergovernmental Panel on Climate Change (IPCC) published a Special Report on Global Warming of 1.5\degree C. This report was called for by the IPCC in December 2015. This report was compiled by the worlds leading scientists comprising 91 authors from 40 countries. This report considers evidence and arguments from over 6,000 scientific sources. \\
\begin{figure}[h!]
\centering
\includegraphics[width=1\textwidth]{riskrisingtemp}
\caption{Risk of rising temperatures \citep{indep2014}}
\end{figure}
The IPCC report states that we could see the 1.5\degree C temperature rise between 12 and 34 years if it continues to increase at the current rate.\\
The report provides several possible pathways to achieve 1.5\degree C, all of which require fossil-fuel use to half in less than 15 years and completely eliminate their use within 30 years. This means no gas, oil, diesel, or coal use in our homes, transport or industry unless the $CO_2$ is captured and stored. We will need to increase bioenergy crop production for energy and additional forestation for natural carbon dioxide absorption. A shift towards renewable energy production and large scale carbon capture and storage will be nessecary. Widespread dietary shifts towards eating less meat and reduced material consumption, would have a significant impact on reducing $CO_2$ emissions. \\
“Without the full involvement and alignment of our technical, social, and political dimensions, 1.5\degree C and even 2\degree C won’t be possible” says Glen Peters, Research Director at Norway’s Center for International Climate Research. \\
Despite the cold hard facts, Donald Trump, ‘has his doubts about climate change’ and thinks that the climate could “change back again”. Trump has also stated that he wishes to withdraw the US from the Paris agreement. \\
\begin{figure}[h!]
\centering
\includegraphics[width=0.5\textwidth]{trumptweet}
\caption{Tweet from Donald Trump \citep{Holden2018}}
\end{figure}
The science and evidence are clear…our species is entering unchartered territory in our existence on planet Earth. I feel we only have one sensible, logical and responsible path to follow at these crossroads – to take immediate action: reduce and eliminate our dependence on fossil fuels, reduce the rate of climate change, engineer a sustainable and renewable future and hopefully save the planet for the future of our species.\\
\\
\\
\\
{\Large Further Reading}\\
% IPCC (2018): SR15 Global Warming of 1.5\degree C. Headline Statements from the Summary for Policymakers. Available online at https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/sr15_headline_statements.pdf, checked on 12/17/2018.\\
National Geographic (2018): Climate change impacts worse than expected, global report warns. National Geographic. Available online at https://www.nationalgeographic.com/environment/2018/10/ipcc-report-climate-change-impacts-forests-emissions/, updated on 12/13/2018, checked on 12/17/2018.\\
unfccc.int (2018): What is the Paris Agreement? Available online at https://unfccc.int/process-and-meetings/the-paris-agreement/what-is-the-paris-agreement, checked on 12/17/2018.\\
Vitousek, Peter M; Mooney, Harold A; Lubchenco, Jane; Melillo, Jerry M (1997): Human Domination of Earths Ecosystems. In Science 277.\\
Wikipedia (2018): Special Report on Global Warming of 1.5\degree C - Wikipedia. Edited by Wikipedia. Available online at https://en.wikipedia.org/w/index.php?oldid=874073532, updated on 12/16/2018, checked on 12/17/2018.\\
WWF (2018): The Effects Of Climate Change. Available online at https://www.wwf.org.uk/effectsofclimatechange, updated on 12/17/2018, checked on 12/17/2018.\\
\bibliography{references}
\end{document}
问题
我不得不弄乱 CO2 来获得下标，但现在当我编译时它会以斜体显示 - 我可以不使用斜体吗？
答案1
今天的标准是使用mhchem（或类似的包），更少的输入
\documentclass{article}
\usepackage[version=4]{mhchem}
\begin{document}
\ce{CO2}
\end{document}
mhchem详细信息请参阅文档。
答案2
另一个类似的包是chemformula（由@Dailef 建议）排版化学公式和反应。链接取自 CTAN Comprehensive TEX Archive Network。
\documentclass{article}
\usepackage{chemformula}
\usepackage{lipsum}
\begin{document}
\ch{CO_2} \lipsum[1]
\ch{CO_2}
\end{document}
答案3
您应该使用$\mathrm{CO}_2$，它可以提供您正在寻找的内容。
