【導(dǎo)讀】tgooutwithmeagainunlessIstoped!IalsonoticedthatIbecamebreathlessquickly,andthatIwasn?Itisnot

　　

【正文】 ou can onl y get the di sease from bl od or sexual fl ui d. Unfortunatel y, peopl e wi th H IV som etim es l ose thei r friends because of prejudi ce. Many peopl e are afrai d that they wi l get H IV/AIDS from those i nfected with H IV/AIDS. For the same reason, som e AIDS pati ents cannot fi nd anyone to l ok after them when they are sick. You can get H IV/AIDS from m osquitoes. WRON G. There i s no evi dence of thi s. Unit 4 TH E EARTH IS BECO MIN G WARMER BUT DO ES IT MATTER? Duri ng the 20th century the tem perature of the earth rose about one degree Fahrenhei t. That probabl y does not seem m uch to you or m e, but i t i s a rapi d i ncrease when pared to other natural changes. So how has thi s e about and does i t m ater? Earth Care?s Sophi e Armstrong expl ores these questi ons. There i s no doubt that the earth i s be ing warm er (see Graph 1) and that i s i t human acti vi ty that has caused thi s gl obal warmi ng rather than a random but natural phenom enon. Al l sci enti sts subscri be to the vi ew that the i ncrease i n the earth?s tem perature i s due to the burni ng of fossi l fuel s l i ke coal, natural gas and oi l to produce energy. Som e byproducts of thi s process are cal ed “greenhouse” gases, the m ost i m portant one of whi ch i s carbon di oxi de. Dr Jani ce Foster expl ai ns: “There is a natural phenom enon that sci enti sts cal l the ?greenhouse effect?. Thi s is when sm al am ounts of gases i n the atm osphere, l ike carbon di oxi de, m ethane and water vapor, trap heat from the sun and therefore warm the earth. Wi thout the ?greenhouse effect?, the earth woul d be about thi rtythree degrees Cel sius cool er than i t i s. So, we need those gases. The probl em begi ns when we add huge quanti ti es of extra carbon di oxi de i nto the atm osphere. It m eans that more heat energy tends to be trapped i n the atm osphere causing the gl obal tem perature to go up.” We know that the l evel s of carbon dioxi de have i ncreased greatl y over the l ast 100 to 150 years. It was a sci enti st cal ed Charles Keel ing, who m ade accurate m easurem ents of the amount of carbon di oxi de i n the atm osphere from 1957 to 1997. H e found that betwen these years the carbon di oxi de i n the atm osphere went up from around 315 parts to around 370 parts per mi li on (see Graph 2). Al sci enti sts accept this data. They al so agre that i t i s the burni ng of m ore and m ore fossil fuels that has resulted i n thi s increase in carbon di oxi de. So how hi gh wi l the tem perature i ncrease go? Dr Jani ce Foster says that over the next 100 years the am ount of warm i ng coul d be as l ow as 1 to 1. 5 degrees Cel si us, but i t coul d be as hi gh as 5 degrees. H owever, the attitudes of sci enti sts towards thi s ri se are pl etel y di fferent. O n the one hand, Dr Foster thi nks that the trend whi ch i ncreases the tem perature by 5 degrees woul d be a catastrophe. She says, “We can?t predi ct the clim ate wel enough to know what to expect, but i t coul d be very serious.” O thers who agree with her thi nk there m ay be a ri se of several m etres i n the sea l evel , or predi ct severe storms, fl ods, droughts, fam ines, the spread of diseases and the di sappearance of speci es. O n the other hand, there are those, li ke Gee H am bl ey, who are oposed to thi s vi ew and beli eve that we shoul d not worry about hi gh l evel s of carbon di oxi de i n the ai r. They predi ct that any warm i ng wil be mi l d with few bad environm ental consequences. In fact, H am bl ey states, ” More carbon di oxi de i s actual ly a posi tive thi ng. It wil m ake pl ants grow qui cker。 crops wil l produce m ore。 i t wil l encourage a greater range of anim al s – al l of whi ch wil l make l ife for hum an beings better. ” Greenhouse gases continue to bui l d up i n the atm osphere. Even i f we start reduci ng the am ount of carbon di oxi de and other greenhouse gases, the cli mate i s goi ng to keep on warm i ng for decades or centuri es. N o one knows the effects of gl obal warm i ng. Does that m ean we shoul d do nothi ng? O r, are the ri sks to great? WH AT CAN WE DO ABOUT GLOBAL WARMING? Dear Earth Care, I am doing a project on behal f of m y schol about gl obal warm i ng. Som etim es I feel that i ndi vi duals can have l i ttl e effect on such huge envi ronm ental probl em s. H owever, I stil l thi nk peopl e shoul d advocate i m provem ents in the way we use energy today. As I?m not sure where to start wi th my project, I woul d appreciate any suggesti ons you m ay have. Thank you O uyang Guang Dear O uyang Guang, There are m any peopl e heart and l ungs or that i t was more di ffi cul t for sm oki ng coupl es to be e pregnant. I certainl y di dn?t know their babi es may have a sm al l er birth wei ght or even be abnorm al in som e way. N ei ther di d I know that m y ci garette smoke coul d affect the heal th of knownsm okers. H owever, what I di d know was that m y girl fri end thought I sm elt terri bl e. She said m y breath and cl othes sm el t, and that the ends of my fi ngers were turni ng yel l ow. She tol d m e that she woul dn?t go out wi th me agai n unless I stopped! I also noti ced that I becam e breathl ess qui ckl y, and that I wasn?t enjoyi ng sport as m uch. When I was taken off the school footbal l team because I was unfi t, I knew it was ti m e to qui t sm oki ng. I am sendi ng you som e advi ce I found on the Inter. It m i ght hel p you to stop and strengthen your resol ve. I do hope so because I want you to l ive as l ong and heal thy a li fe as I have. Love from Grandad H ow can you stop sm oking? It is not easy to stop sm oki ng, but m il li ons have managed to qui t and so can you. H ere are a few suggesti ons. Prepare yoursel f. Deci de on a day to qui t. Don?t choose a day that you know i s goi ng to be stressful, such as the day of an exam. Make a l ist of al l the b